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• What is descriptive research?

Last updated

5 February 2023

Reviewed by

Cathy Heath

Descriptive research is a common investigatory model used by researchers in various fields, including social sciences, linguistics, and academia.

Read on to understand the characteristics of descriptive research and explore its underlying techniques, processes, and procedures.

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Descriptive research is an exploratory research method. It enables researchers to precisely and methodically describe a population, circumstance, or phenomenon.

As the name suggests, descriptive research describes the characteristics of the group, situation, or phenomenon being studied without manipulating variables or testing hypotheses . This can be reported using surveys , observational studies, and case studies. You can use both quantitative and qualitative methods to compile the data.

Besides making observations and then comparing and analyzing them, descriptive studies often develop knowledge concepts and provide solutions to critical issues. It always aims to answer how the event occurred, when it occurred, where it occurred, and what the problem or phenomenon is.

• Characteristics of descriptive research

The following are some of the characteristics of descriptive research:

Quantitativeness

Descriptive research can be quantitative as it gathers quantifiable data to statistically analyze a population sample. These numbers can show patterns, connections, and trends over time and can be discovered using surveys, polls, and experiments.

Qualitativeness

Descriptive research can also be qualitative. It gives meaning and context to the numbers supplied by quantitative descriptive research .

Researchers can use tools like interviews, focus groups, and ethnographic studies to illustrate why things are what they are and help characterize the research problem. This is because it’s more explanatory than exploratory or experimental research.

Uncontrolled variables

Descriptive research differs from experimental research in that researchers cannot manipulate the variables. They are recognized, scrutinized, and quantified instead. This is one of its most prominent features.

Cross-sectional studies

Descriptive research is a cross-sectional study because it examines several areas of the same group. It involves obtaining data on multiple variables at the personal level during a certain period. It’s helpful when trying to understand a larger community’s habits or preferences.

Carried out in a natural environment

Descriptive studies are usually carried out in the participants’ everyday environment, which allows researchers to avoid influencing responders by collecting data in a natural setting. You can use online surveys or survey questions to collect data or observe.

Basis for further research

You can further dissect descriptive research’s outcomes and use them for different types of investigation. The outcomes also serve as a foundation for subsequent investigations and can guide future studies. For example, you can use the data obtained in descriptive research to help determine future research designs.

• Descriptive research methods

There are three basic approaches for gathering data in descriptive research: observational, case study, and survey.

You can use surveys to gather data in descriptive research. This involves gathering information from many people using a questionnaire and interview .

Surveys remain the dominant research tool for descriptive research design. Researchers can conduct various investigations and collect multiple types of data (quantitative and qualitative) using surveys with diverse designs.

You can conduct surveys over the phone, online, or in person. Your survey might be a brief interview or conversation with a set of prepared questions intended to obtain quick information from the primary source.

Observation

This descriptive research method involves observing and gathering data on a population or phenomena without manipulating variables. It is employed in psychology, market research , and other social science studies to track and understand human behavior.

Observation is an essential component of descriptive research. It entails gathering data and analyzing it to see whether there is a relationship between the two variables in the study. This strategy usually allows for both qualitative and quantitative data analysis.

Case studies

A case study can outline a specific topic’s traits. The topic might be a person, group, event, or organization.

It involves using a subset of a larger group as a sample to characterize the features of that larger group.

You can generalize knowledge gained from studying a case study to benefit a broader audience.

This approach entails carefully examining a particular group, person, or event over time. You can learn something new about the study topic by using a small group to better understand the dynamics of the entire group.

• Types of descriptive research

There are several types of descriptive study. The most well-known include cross-sectional studies, census surveys, sample surveys, case reports, and comparison studies.

Case reports and case series

In the healthcare and medical fields, a case report is used to explain a patient’s circumstances when suffering from an uncommon illness or displaying certain symptoms. Case reports and case series are both collections of related cases. They have aided the advancement of medical knowledge on countless occasions.

The normative component is an addition to the descriptive survey. In the descriptive–normative survey, you compare the study’s results to the norm.

Descriptive survey

This descriptive type of research employs surveys to collect information on various topics. This data aims to determine the degree to which certain conditions may be attained.

You can extrapolate or generalize the information you obtain from sample surveys to the larger group being researched.

Correlative survey

Correlative surveys help establish if there is a positive, negative, or neutral connection between two variables.

Performing census surveys involves gathering relevant data on several aspects of a given population. These units include individuals, families, organizations, objects, characteristics, and properties.

During descriptive research, you gather different degrees of interest over time from a specific population. Cross-sectional studies provide a glimpse of a phenomenon’s prevalence and features in a population. There are no ethical challenges with them and they are quite simple and inexpensive to carry out.

Comparative studies

These surveys compare the two subjects’ conditions or characteristics. The subjects may include research variables, organizations, plans, and people.

Comparison points, assumption of similarities, and criteria of comparison are three important variables that affect how well and accurately comparative studies are conducted.

For instance, descriptive research can help determine how many CEOs hold a bachelor’s degree and what proportion of low-income households receive government help.

• Pros and cons

The primary advantage of descriptive research designs is that researchers can create a reliable and beneficial database for additional study. To conduct any inquiry, you need access to reliable information sources that can give you a firm understanding of a situation.

Quantitative studies are time- and resource-intensive, so knowing the hypotheses viable for testing is crucial. The basic overview of descriptive research provides helpful hints as to which variables are worth quantitatively examining. This is why it’s employed as a precursor to quantitative research designs.

Some experts view this research as untrustworthy and unscientific. However, there is no way to assess the findings because you don’t manipulate any variables statistically.

Cause-and-effect correlations also can’t be established through descriptive investigations. Additionally, observational study findings cannot be replicated, which prevents a review of the findings and their replication.

The absence of statistical and in-depth analysis and the rather superficial character of the investigative procedure are drawbacks of this research approach.

• Descriptive research examples and applications

Several descriptive research examples are emphasized based on their types, purposes, and applications. Research questions often begin with “What is …” These studies help find solutions to practical issues in social science, physical science, and education.

Here are some examples and applications of descriptive research:

Determining consumer perception and behavior

Organizations use descriptive research designs to determine how various demographic groups react to a certain product or service.

For example, a business looking to sell to its target market should research the market’s behavior first. When researching human behavior in response to a cause or event, the researcher pays attention to the traits, actions, and responses before drawing a conclusion.

Scientific classification

Scientific descriptive research enables the classification of organisms and their traits and constituents.

Measuring data trends

A descriptive study design’s statistical capabilities allow researchers to track data trends over time. It’s frequently used to determine the study target’s current circumstances and underlying patterns.

Conduct comparison

Organizations can use a descriptive research approach to learn how various demographics react to a certain product or service. For example, you can study how the target market responds to a competitor’s product and use that information to infer their behavior.

• Bottom line

A descriptive research design is suitable for exploring certain topics and serving as a prelude to larger quantitative investigations. It provides a comprehensive understanding of the “what” of the group or thing you’re investigating.

This research type acts as the cornerstone of other research methodologies . It is distinctive because it can use quantitative and qualitative research approaches at the same time.

What is descriptive research design?

Descriptive research design aims to systematically obtain information to describe a phenomenon, situation, or population. More specifically, it helps answer the what, when, where, and how questions regarding the research problem rather than the why.

How does descriptive research compare to qualitative research?

Despite certain parallels, descriptive research concentrates on describing phenomena, while qualitative research aims to understand people better.

How do you analyze descriptive research data?

Data analysis involves using various methodologies, enabling the researcher to evaluate and provide results regarding validity and reliability.

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Descriptive Research: Definition, Characteristics, Methods + Examples

Suppose an apparel brand wants to understand the fashion purchasing trends among New York’s buyers, then it must conduct a demographic survey of the specific region, gather population data, and then conduct descriptive research on this demographic segment.

The study will then uncover details on “what is the purchasing pattern of New York buyers,” but will not cover any investigative information about “ why ” the patterns exist. Because for the apparel brand trying to break into this market, understanding the nature of their market is the study’s main goal. Let’s talk about it.

What is descriptive research?

Descriptive research is a research method describing the characteristics of the population or phenomenon studied. This descriptive methodology focuses more on the “what” of the research subject than the “why” of the research subject.

The method primarily focuses on describing the nature of a demographic segment without focusing on “why” a particular phenomenon occurs. In other words, it “describes” the research subject without covering “why” it happens.

Characteristics of descriptive research

The term descriptive research then refers to research questions, the design of the study, and data analysis conducted on that topic. We call it an observational research method because none of the research study variables are influenced in any capacity.

Some distinctive characteristics of descriptive research are:

• Quantitative research: It is a quantitative research method that attempts to collect quantifiable information for statistical analysis of the population sample. It is a popular market research tool that allows us to collect and describe the demographic segment’s nature.
• Uncontrolled variables: In it, none of the variables are influenced in any way. This uses observational methods to conduct the research. Hence, the nature of the variables or their behavior is not in the hands of the researcher.
• Cross-sectional studies: It is generally a cross-sectional study where different sections belonging to the same group are studied.
• The basis for further research: Researchers further research the data collected and analyzed from descriptive research using different research techniques. The data can also help point towards the types of research methods used for the subsequent research.

Applications of descriptive research with examples

A descriptive research method can be used in multiple ways and for various reasons. Before getting into any survey , though, the survey goals and survey design are crucial. Despite following these steps, there is no way to know if one will meet the research outcome. How to use descriptive research? To understand the end objective of research goals, below are some ways organizations currently use descriptive research today:

• Define respondent characteristics: The aim of using close-ended questions is to draw concrete conclusions about the respondents. This could be the need to derive patterns, traits, and behaviors of the respondents. It could also be to understand from a respondent their attitude, or opinion about the phenomenon. For example, understand millennials and the hours per week they spend browsing the internet. All this information helps the organization researching to make informed business decisions.
• Measure data trends: Researchers measure data trends over time with a descriptive research design’s statistical capabilities. Consider if an apparel company researches different demographics like age groups from 24-35 and 36-45 on a new range launch of autumn wear. If one of those groups doesn’t take too well to the new launch, it provides insight into what clothes are like and what is not. The brand drops the clothes and apparel that customers don’t like.
• Conduct comparisons: Organizations also use a descriptive research design to understand how different groups respond to a specific product or service. For example, an apparel brand creates a survey asking general questions that measure the brand’s image. The same study also asks demographic questions like age, income, gender, geographical location, geographic segmentation , etc. This consumer research helps the organization understand what aspects of the brand appeal to the population and what aspects do not. It also helps make product or marketing fixes or even create a new product line to cater to high-growth potential groups.
• Validate existing conditions: Researchers widely use descriptive research to help ascertain the research object’s prevailing conditions and underlying patterns. Due to the non-invasive research method and the use of quantitative observation and some aspects of qualitative observation , researchers observe each variable and conduct an in-depth analysis . Researchers also use it to validate any existing conditions that may be prevalent in a population.
• Conduct research at different times: The analysis can be conducted at different periods to ascertain any similarities or differences. This also allows any number of variables to be evaluated. For verification, studies on prevailing conditions can also be repeated to draw trends.

Advantages of descriptive research

Some of the significant advantages of descriptive research are:

• Data collection: A researcher can conduct descriptive research using specific methods like observational method, case study method, and survey method. Between these three, all primary data collection methods are covered, which provides a lot of information. This can be used for future research or even for developing a hypothesis for your research object.
• Varied: Since the data collected is qualitative and quantitative, it gives a holistic understanding of a research topic. The information is varied, diverse, and thorough.
• Natural environment: Descriptive research allows for the research to be conducted in the respondent’s natural environment, which ensures that high-quality and honest data is collected.
• Quick to perform and cheap: As the sample size is generally large in descriptive research, the data collection is quick to conduct and is inexpensive.

Descriptive research methods

There are three distinctive methods to conduct descriptive research. They are:

Observational method

The observational method is the most effective method to conduct this research, and researchers make use of both quantitative and qualitative observations.

A quantitative observation is the objective collection of data primarily focused on numbers and values. It suggests “associated with, of or depicted in terms of a quantity.” Results of quantitative observation are derived using statistical and numerical analysis methods. It implies observation of any entity associated with a numeric value such as age, shape, weight, volume, scale, etc. For example, the researcher can track if current customers will refer the brand using a simple Net Promoter Score question .

Qualitative observation doesn’t involve measurements or numbers but instead just monitoring characteristics. In this case, the researcher observes the respondents from a distance. Since the respondents are in a comfortable environment, the characteristics observed are natural and effective. In a descriptive research design, the researcher can choose to be either a complete observer, an observer as a participant, a participant as an observer, or a full participant. For example, in a supermarket, a researcher can from afar monitor and track the customers’ selection and purchasing trends. This offers a more in-depth insight into the purchasing experience of the customer.

Case study method

Case studies involve in-depth research and study of individuals or groups. Case studies lead to a hypothesis and widen a further scope of studying a phenomenon. However, case studies should not be used to determine cause and effect as they can’t make accurate predictions because there could be a bias on the researcher’s part. The other reason why case studies are not a reliable way of conducting descriptive research is that there could be an atypical respondent in the survey. Describing them leads to weak generalizations and moving away from external validity.

Survey research

In survey research, respondents answer through surveys or questionnaires or polls . They are a popular market research tool to collect feedback from respondents. A study to gather useful data should have the right survey questions. It should be a balanced mix of open-ended questions and close ended-questions . The survey method can be conducted online or offline, making it the go-to option for descriptive research where the sample size is enormous.

Examples of descriptive research

Some examples of descriptive research are:

• A specialty food group launching a new range of barbecue rubs would like to understand what flavors of rubs are favored by different people. To understand the preferred flavor palette, they conduct this type of research study using various methods like observational methods in supermarkets. By also surveying while collecting in-depth demographic information, offers insights about the preference of different markets. This can also help tailor make the rubs and spreads to various preferred meats in that demographic. Conducting this type of research helps the organization tweak their business model and amplify marketing in core markets.
• Another example of where this research can be used is if a school district wishes to evaluate teachers’ attitudes about using technology in the classroom. By conducting surveys and observing their comfortableness using technology through observational methods, the researcher can gauge what they can help understand if a full-fledged implementation can face an issue. This also helps in understanding if the students are impacted in any way with this change.

Some other research problems and research questions that can lead to descriptive research are:

• Market researchers want to observe the habits of consumers.
• A company wants to evaluate the morale of its staff.
• A school district wants to understand if students will access online lessons rather than textbooks.
• To understand if its wellness questionnaire programs enhance the overall health of the employees.

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Description in Scientific Research: Observations and multiple working hypotheses

by Anne E. Egger, Ph.D., Anthony Carpi, Ph.D.

Listen to this reading

Did you know that not all scientists conduct experiments? Anthropologist Jane Goodall was doing scientific research when she spent years in African forests watching chimpanzees and recording her systematic observations. Description has been used to develop theories in many scientific fields, including astronomy, geology, and primatology.

Description involves the systematic observation and cataloging of components of a natural system in a manner that can be utilized and replicated by other scientists.

Description is commonly used as a research method to explain unique natural systems (such as in ecology or chemistry), large-scale phenomena (such as in astronomy), or past events (such as in geology or forensic science).

An eclipse is a dramatic event: the sky goes dark during the day in a solar eclipse , and the moon turns red during a lunar eclipse . As a result, many cultures have revered both solar and lunar eclipses, and their occurrences are noted frequently in prehistoric art, oral histories, and historical records . The Chinese began systematically recording the time and location of eclipses on what they called oracle bones as early as 2000 BCE . Astronomers in ancient Mesopotamia kept detailed records of lunar eclipses engraved on 70 tablets dating back to 600 BCE (such as shown in Figure 1), and these records were used to accurately predict future eclipses (Steele, 2000). By the 4 th century BCE, the Mesopotamians had developed a comprehensive lunar theory from these observations – a mathematical description of the movements of the sun and moon through the sky – that was the first of its kind (Britton, 2007).

These records define an early stage in the development of the science of astronomy, which relied on quantitative description as a research method . The ancient astronomers observed and described the motion of objects in the sky, noted the time and location of events, developed mathematical models based on the phenomena they observed, and then used those models to predict future eclipses through mathematical computations.

Figure 1: Clay tablet listing eclipses between 518 and 465 BCE from the ancient city of Babylon in Mesopotamia.

Around 340 BCE , the Greek astronomer Eudoxus developed his own geometrical theory of the universe (Goldstein & Bowen, 1983): He proposed that the universe consisted of nested spheres with a non-moving Earth at the center. This theory was based on his recorded observations of the paths that planets took through the sky, and the relationships of the planets to the Earth, moon, and sun. However, Eudoxus was not able to quantify these relationships and thus was unable to use his observations predictively. In the 2 nd century BCE, the Mesopotamian records reached Greece, and the mathematician Hipparchus revolutionized Greek astronomy by combining Greek and Mesopotamian observations and descriptions.

Though the exact method of transmission of ideas is not clear, the presence and use of these long-term descriptive records was at the core of the development of the science of astronomy. Those early data are so significant, in fact, that they are still being revisited today: Both the Chinese and Mesopotamian eclipse catalogs have been used by modern scientists to approach new scientific questions, like measuring the rate of slowing of Earth's rotation over time (Pang, Yau, Chou, & Wolff, 1988).

• Description as a scientific research method

These early astronomers used descriptions of natural phenomena to make scientific inferences about broad physical principles , like the rotation of the Earth or the nature of the solar system . As discussed in The Practice of Science module, all research methods involve data gathering and hypothesis development and testing, and the descriptive method is no different. This method usually involves the following steps:

• The systematic observation and detailed description of a phenomenon in a manner that could be replicated – for example, the frequency of lunar eclipses , the composition and orientation of rock layers in Utah, or the behavior of chimpanzees in the wild.
• These and sometimes other lines of evidence are used to develop a hypothesis or multiple working hypotheses to explain the phenomenon.
• Additional observations or other types of research are conducted to test the hypothesis or to determine the likelihood of the competing hypotheses.
• Eventually, an explanatory theory that fits the observations and evidence can be developed.

This is an iterative process that happens on many scales: The entire process may happen within a few days for one scientist, or over many decades or centuries and involving the contributions of many scientists, sometimes from many fields of science.

Descriptive studies can also be exploratory rather than driven by hypothesis testing. The US Geological Survey, for example, maintains stream gauges on many streams and rivers in the United States, which record daily observations of the amount of water flowing at that point. These were not established to test any specific hypothesis, but simply to keep a record. The records have proven useful in addressing questions about flood recurrence intervals, daily and seasonal fluctuations in stream flow, and other watershed-related questions. Not all descriptions of streamflow are scientific, however. Part of the reason that these records are so useful is because the descriptions are systematic, and involve the same rigor and consistency that is required in designing a well-controlled experiment (see our Experimentation in Science module) or in building a useful mathematical model (see our Modeling in Science module). The location of each stream gauge was surveyed and calibrated to accurately record the flow. Streamflow is measured at the same time each day, and in the same location. The same parameters are recorded each day at each station, including stream height, water temperature, and volume of flow. Without that consistency, it would be difficult to establish the accuracy and reliability of the data that were collected.

Though it can stand alone as a research method , systematic description is often a component of other types of scientific research. Scientists who conduct experiments must first study and describe the system with which they experiment, researchers who initiate comparative studies need descriptive data regarding the population they are investigating, and scientists who build models must have an accurate representation of the system they are modeling.

Comprehension Checkpoint

• Description in practice: G.K. Gilbert and the geology of the Henry Mountains

In the United States, description was used as a scientific research method extensively during the exploration of the west. In the 1860s, the US government launched a series of four surveys into the American west: The King, Wheeler, Hayden, and Powell surveys lasted from 1860 until 1879. Each of these survey teams included a geologist whose job was to observe and describe the landscape . The geological exploration of the Henry Mountains in southern Utah provides insight into the research method of description and one of its most respected practitioners, G.K. Gilbert.

Figure 2: A picture of the Henry Mountains in Utah. Image courtesy of Ian Parker, http://parkerlab.bio.uci.edu/.

On his two trips down the Colorado River in the 1870s, John Wesley Powell had noted the Henry Mountains with interest. They lay west of the river as it wound through Glen Canyon, rising abruptly from the surrounding mesas. Their dark peaks contrasted sharply with the light-colored, layered rocks that surrounded the river on all sides (see the photo in Figure 2). Powell did not have time to explore the mountains himself, and thus gave the task to Grove Karl Gilbert , a young geologist who had worked with him previously. Gilbert spent a week in the mountains in 1875, and returned for a month in 1876, emerging with several notebooks filled with carefully recorded notes, sketches, and hypotheses . In August of 1875, he wrote the following observations:

…The rock which rises towards Hillers from the south is the B Cliff. It is lost in the 'debris' without increasing the dip (7°) with which it approaches. But beyond are red and white sands – [deeper] rocks tilted almost to the vertical and interspersed with dikes. Moreover these sandstone hogbacks seem to trend in a curve around the mountain as far as they extend.

He made a sketch, shown in Figure 3 below, in which he indicated where he had taken measurements and summarized his descriptions.

Figure 3: G. K. Gilbert's sketch of the rocks surrounding Mt. Hillers to accompany his notes; the small letter b on the left side of the diagram corresponds with the "B Cliff" in his notes. (Hunt, 1988)

Gilbert collected samples of each of the rock types labeled in Figure 3 and described them. The layered rocks (labeled b, c, d, s, and p in Figure 3) were all sedimentary rocks that he had seen before in his travels, and he described them by color, grain size, and the fossils they contained. The core of Mt. Hillers was different, however: an igneous rock formed from cooling magma . He described this rock as "a pale gray paste with large white crystals of feldspar and crystals large and small of hornblende." Based on this composition he determined it was trachyte , labeled t in Figure 3. Gilbert sketched the same mountain from several different angles and collected measurements on the orientation of rock layers all the way around it, while also collecting basic survey data like elevation.

Figure 4: Gilbert's drawing representing a hypothesis for the formation of Mt. Hillers.

Just a few notebook pages and one day later, Gilbert takes the first leap from observation and data collection to hypothesis . He sketches a cross-section that is no longer a faithful depiction of the landscape , but is a hypothesis for the formation of Mt. Hillers (Figure 4). This initial model takes all of his observations thus far into account: the gentle slopes of the sedimentary rock units leading up to the peak, the steeply dipping rocks that continue all the way around the mountain, and the igneous rock at the center. He devotes little text to explaining his idea at this point, writing only about a "reservoir" of magma forming below the surface and deforming the rock layers above it. He knew he had more data to collect in order to test this initial hypothesis; the next day, he wrote in his notes, "I don't understand the NE side of Hillers." He could not yet explain what was going on there through his initial hypothesis.

Gilbert had only a few days left in the Henry Mountains that summer as he continued on his exploratory journey. The next year (1876) he returned, however, to the task of collecting more data to revise his initial, simple hypothesis . After a month of collecting survey data and rock unit orientations, Gilbert and his team were stuck in camp because of rain and snow. Gilbert took the opportunity to summarize his findings and display the development of his thinking over the course of his explorations. He re-drew the sketch from the previous year and wrote an explanation for his new model:

The simplest type of Henry Mt. structure is a lenticular mass of trap [an early word for igneous rock] above which the strata were arched... The form of the trap mass is never fully shown but it can be described in a general way in several cases... Injections are combined and grouped variously. A trap mass with sheets above and below may be regarded as a system of exudations from one chimney.

He includes a more realistic representation of the process as it applies to the Henry Mountains specifically (Figure 5). Gilbert then poses a question about these intrusions: Why didn't the magma reach the surface?

Figure 5: Gilbert's 1876 drawing representing a revised hypothesis for the formation of the Henry Mountains.

Gilbert published his "Report on the Geology of the Henry Mountains" in 1877 (Gilbert, 1877). In the publication, he named this newly discovered type of intrusion a laccolite (later changed to laccolith). He formalized his field sketches, measurements, and research questions into a coherent theory about the formation of the Henry Mountains and noted that many other mountains in the region were likely formed through the same process . He proposed two different answers for his question about the underlying causes of the intrusion relating to relative densities and the "penetrability" of the sedimentary rocks, but his question has still not been resolved today. Gilbert's report is considered a key milestone in geology, not only for the new type of intrusion he proposed, but for the highly systematic way in which he used the descriptive method of science; as a result, Gilbert went on to become a highly valued and respected leader of the new US Geological Survey and two-time president of the Geological Society of America.

Gilbert's work also laid the foundation for further research on the Henry Mountains. More detailed measurements of the folding and faulting in the rock layers gave strong support to Gilbert's laccolith hypothesis (Jackson & Pollard, 1988). More recently, researchers have experimented with physical analogue models to try to understand why the magma did not make it to the surface by building sedimentary layers out of sand and injecting the layers from below with silica gel to simulate magma (Roman-Berdiel, Gapais, & Brun, 1995).

• Description across disciplines

Description as a research method is not a thing of the past, nor does it consist solely of sketches. Ongoing measurements of CO 2 concentrations in the atmosphere , such as those begun by Charles Keeling on the Hawaiian volcano Mauna Loa in 1958, are a quantitative description of the composition of the atmosphere over time (see The Carbon Cycle module). These daily, worldwide measurements have allowed climate scientists to develop hypotheses about the atmospheric response to volcanic eruptions, pollutants, and the steadily increasing emissions of greenhouse gases. The atmospheric record has been extended back 650,000 years through the sampling and description of CO 2 concentrations in air bubbles trapped in ice cores drilled in Greenland and Antarctica (Figure 6). These data reveal a cyclical pattern in CO 2 concentrations that has helped climate scientists develop an understanding of long-term climate. Based on these findings, climatologists can develop models to assess the possible impacts of a continued increase in CO 2 concentration in the atmosphere.

Figure 6: Data from the European Project for Ice-Coring in Antarctica (EPICA), showing CO 2 concentrations over time (graph is from Siegenthaler et al., 2005 ). The three different colors represent data collected from three separate ice cores.

In contrast with experimentation, sometimes the main goal of the descriptive method is explicitly to avoid manipulating any variables , such as in some ecological studies that seek to describe the natural interactions between organisms in the environment . Jane Goodall 's goal in the Gombe National Park in Tanzania when she began working there in the 1960s was the non-invasive observation of chimpanzees in the wild. One of her first papers, "Tool-using and aimed throwing in a community of free-living chimpanzees," published in 1964, opened with the fact that tool-use had been observed in chimpanzees in captivity, but many people wanted to know if the behavior existed in wild populations .

In order to answer this question, Goodall observed chimpanzees in their natural habitat and took detailed notes. Goodall's work involved long days, weeks, and months in the field. In the beginning of her study, she simply sat near the chimps to assure that the animals would become comfortable with her presence and would act normally, as she did not want her presence to be a variable affecting their behavior. Goodall then placed boxes full of bananas in areas where she knew the chimpanzees would find them. The kinds of data she presented in her paper included descriptions like the following:

After pulling and pushing at the boxes for up to 5 min., each one broke off a stick and stripped it of its leaves. Two individuals then tried to push their sticks under the box lids.... None of the three had seen either of the others trying to solve the problem in this way.

It is important to recognize that Goodall did manipulate the environment (she gave the chimpanzees something new to look at – boxes of bananas), but she did not attempt to manipulate their behavior – that was the object of her observations and descriptions. She used these and other observations to develop new ideas about chimpanzees as tool-users who think independently and can learn from one another (Goodall, 1964), revolutionizing our understanding of non-human primates and human origins.

In fact, Goodall was performing an experiment , in a sense, with the chimpanzees: What will they do with a sealed box of bananas? That particular research question falls somewhere on a continuum between experimentation and description, and highlights how different research methods complement each other. It is particularly common that experimentation and description overlap: Another example is NASA 's Deep Impact mission, which is described in our Experimentation in Science module.

• Limitations of the descriptive method

Description is very widely used throughout scientific research , and there are few limitations on its use. It is a very useful research method for questions where experimentation is impossible, such as determining events in the history of Earth. Despite the wide applicability of the method in science, it is challenging to establish cause and effect relationships through description alone. Instead, descriptive studies lead most often to information about the function or form of phenomena, like Gilbert's work, and the establishment of physical, spatial, and temporal relationships.

Systematic description can also easily lead to unscientific explanations, as is evident in the mythologies and legends of many cultures. The early Greeks were excellent observers of their environment , and they developed mythological explanations for natural processes that we now understand in a scientific sense. For example, like most agricultural peoples, the Greeks observed and monitored the change of the seasons, the regular cycle of budding and growth in the spring, followed by a season of abundance in the summer, the fall harvest, and barren fields in the winter. These observations are encapsulated in the myth of Demeter, the goddess of agriculture, and her daughter Persephone, who was kidnapped by Hades and taken to the Underworld. In the myth, Demeter strikes a deal with Hades to share Persephone – for six months of the year, Persephone lives with her mother on the surface , and Demeter's happiness is reflected in the seasons of spring and summer, while the six months when Persephone returns to the Underworld are marked by Demeter's grief, and the crops wither and die. Clearly, the observations of seasonal changes are valid, but the mythological explanation is not scientific.

In some cases, even descriptions that weren't meant to be scientific at the time can be utilized by scientists later. For example, many historical figures have been diagnosed with diseases or afflictions long after their deaths by historians and scientists who peruse diaries, letters, and other primary sources for descriptions of symptoms.

In 1979, Peter Spargo, a chemist at the University of Cape Town, teamed with a forensic scientist, C.A. Pounds, to determine the cause of an episode of "madness" experienced by Isaac Newton in 1692-93. Many historians had noted oddities in Newton 's behavior during this time as reflected in his letters and records . Based on the descriptions of his actions contained in these letters and records, Spargo and Pounds summarized the symptoms of Newton 's illness as "severe insomnia, extreme sensitivity in personal relations, loss of appetite, delusions of persecution, and amnesia." They noted that during this same time period, Newton was engaged in intense alchemical experimentation and hypothesized he was experiencing heavy metal poisoning (Spargo & Pounds, 1979). In other words, though the descriptions of Newton's behavior were not meant to thoroughly document his ailment, they were still useful in developing a scientific hypothesis . Spargo and Pounds were able to test their hypothesis by obtaining a sample of Newton's hair, which indeed revealed significantly elevated levels of mercury, arsenic, gold, chlorine, antimony, and lead – all metals capable of producing temporary neurological disorders such as those he experienced.

• Description in modern practice

Although many scientists still sketch their descriptions with pencil and paper, the tools available for descriptive studies have proliferated and grown more powerful. For example, the use of X-ray diffraction allows geologists to go beyond a field description of a rock to a detailed description of the chemical make-up of individual minerals (see our module, The Silicate Minerals ). This same technique allowed Crick, Franklin, Watson, and Wilson to describe the structure of the DNA molecule as a double helix (see our DNA II: The Structure of DNA module). Other instruments, like mass spectrometers make it possible to determine the absolute ages of things like lavas from volcanic eruptions and bones from archaeological sites, whereas scientists like Gilbert, who worked before such technology was invented, could only assign relative ages to the rocks he studied. Many of our most advanced and costly technologies are based on making highly accurate descriptions: For example, global positioning satellite (GPS) technology allows ecologists, oceanographers , and many others to accurately pinpoint their sample locations and make more detailed analyses of spatial data ; magnetic resonance imaging (or MRI) allows us to see our the organs inside our bodies for more accurate medical diagnoses. These techniques are in use today in a variety of scientific disciplines, bringing new understanding to large-scale, complex, interacting systems .

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