Revised: August 7, 2019 1

ENVR 1401 – BACKGROUND

Lab 1 – Scientific Method

Learning Objectives:

1. Outline the steps to the scientific method.

2. Identify testable observations.

3. Distinguish between dependent and independent variables.

4. Collect, organize, and present scientific data.

Overview

This activity explores the concept and application of the scientific method. To distinguish true cause- effect

relationships from associations or perceptions, phenomena must be investigated using designed experiments

and careful observations that can be repeated by others.

The scientific method is typically discussed as a standardized, linear process that includes the following steps and involves specific skills:

1. Make observations or gather data ➔ often leads to a question

2. Formulate a hypothesis which leads to an associated prediction

3. Design an appropriate test/experiment to assess the hypothesis/prediction

4. Conduct test/experiment, record and analyze the results (including mathematical and statistical evaluation)

5. Interpret the results and draw conclusions ➔ accept, revise, or reject the hypothesis

6. Reporting the results (e.g., laboratory report, formal memorandum, peer reviewed article)

Revised: August 7, 2019 2

But, as shown in the flow chart, the process is not linear. It is cyclical because good science stimulates

further thought and mandates that ideas be challenged and further tested to demonstrate that the results can be repeated (iterative process). A scientific hypothesis is an informed, testable, and predictive explanation

of a natural phenomenon, process or event. If, upon testing, the scientific hypothesis fails the test, it must be

rejected or may be modified and subject to further testing. Models are mathematical or conceptual

hypotheses that provide useful perspectives, though often limited by oversimplification of the process they represent.

If, however, a scientific hypothesis continues to pass repeated tests and the predictions have been verified,

then it is considered a corroborated hypothesis. A highly corroborated hypothesis which has been repeatedly tested and is supported by significant reliable evidence is considered a scientific fact or natural

law, such as the existence of gravity as a property of all matter.

A unifying and consistent explanation of fundamental natural processes or phenomena that is constructed of

corroborated hypotheses and scientific facts is a scientific theory. Scientific theories, such as quantum

mechanics, thermodynamics, plate tectonics, evolution, or relativity, are the most reliable and comprehensive form of human knowledge. And, as we gain more knowledge through the application of the

scientific method, our understanding of the universe in which we live and our theories on how it functions

and evolves must continue to be refined.

Further value of the scientific method is derived from honing and applying necessary skills to develop

scientific knowledge:

◼ making, recording, and reporting unbiased measurements

◼ classifying data

◼ translating and analyzing information

◼ applying deductive and inductive logic

◼ critical, interpretive, and creative thinking

◼ identifying and controlling variables

The scientific method established an approach to a problem and enforces scientific thought that attempts to

eliminate bias in the resulting data and conclusions. Science relies upon empirical evidence which is

observable and measurable by more than one researcher. But as humans, we tend to view the world and

solutions to problems within our personal framework. For example, if a town along the river is repeatedly

flooded, then the structural engineer believes the problem will be solved by building a dam and the politician may believe than any solution is too expensive or unpopular and would be detrimental to being re-elected. In

contrast, the natural resource manager may prefer limiting urban development and re- establishing native

habitat. The propensity of humans to perceive the world from their perspective is good reason to have a healthy dose of skepticism — to constantly question your beliefs, observations, and conclusions.

Scientific methodology has a long history that dates back over 1,000 years, with many cultures and

individuals contributing to its development. Ancient Egyptian papyri describe methods of medical diagnosis and empiricism. Empirical evidence found in nature allows us to describe and explain natural processes and

natural laws. The first experimental scientific method was developed by Muslim scientists. Alhazen (Ibn al-

Haytham, 965-1039) is credited with introducing experimentation and quantification in his work on optics, among his significant contributions to astronomy, engineering, physics, medicine, and science in general. In

Europe the Renaissance resulted in renewed interest in the ideas and science developed during the Greek and

Roman empires.

The logic and philosophical approaches of Aristotle and Socrates were improved upon by Francis Bacon in

the early 1600s. Descartes formalized the guiding principles for the scientific method, strengthening the link between science and mathematics. Galileo also showed the importance of testing or experimenting to look

for the opposite of a consequence to potentially disprove an idea. In the late 1800s, Peirce outlined objective

methods using deduction and induction as complementary approaches, as well as outlining the basic scheme for hypothesis and testing that we currently use.

Revised: August 7, 2019 3

Deduction and induction are types of argument or logical approaches. Deduction, in simplest terms, is the

logical process of arriving at a conclusion based on premises (e.g., facts, statements, laws) that have been verified. Induction, in simplest terms, is the logical process of arriving at a conclusion based on premises

that are assumed to be true; therefore, some conclusions of inductive thought processes may be false.

Deduction is generally described as moving from the more general to the more specific. For example, the Law of Gravity expresses the force that attracts objects to each other. In common terms, it explains why

objects fall toward Earth or, in the environment, why water flows downhill. Based on the Law of Gravity we

would deduce that weathered soil materials would also move down slope. Induction is generally described

as moving from specific observations or details to a general statement. For example, we begin by making observations or measurements, detect patterns or regularities, and develop a general conclusion. In

application, if you touch a stove ten times and each time you touch the stove, you burn your hand. You

might conclude that the stove is always hot. But this conclusion may or may not be true.

The scientific method can never “absolutely prove” or provide “truth” to understand. To paraphrase

Einstein, “No amount of experimentation can ever prove me right; a single experiment can prove me

wrong.” For this reason, and to overcome the human bias for seeing what we want to see, we need to consider that a cause-effect relationship exists (hypothesis) AND consider that a perceived cause-effect

relationship does not exist (null hypothesis).

Step 1 – Make observations or gather data

Awareness of our environment may lead to posing a question. Such awareness may result from making

observations around us, gathering preliminary data that reflect environmental conditions, or by researching

and reading published work of others. This approach often leads to the recognition of a broad problem that warrants further investigation. For example, “Is our water reservoir clean and safe?” Exploring this question

by further reading and research may allow refinement of the question. For example, “Is chemical “A” in our

water supply reservoir?” The question will provide a basis for further investigation.

Step 2 – Formulate a hypothesis which leads to an associated prediction

To formulate a hypothesis, it is important to focus the posed question and to define a specific parameter to

be investigated with an expected result. The prediction may be 1) there will be a specific outcome in the

experiment, 2) there will be a statistical difference between the tested subject and a control, or 3) there will

be no difference between the tested subject and the control. Formulation of the hypothesis is critical because it will help to define and outline the experiment in terms of the specific parameters (independent and

dependent variables) that are being assessed.

The hypothesis is a statement of the most likely outcome of the experiment. More appropriately, the

hypothesis (designated by HA) should be viewed as a prediction that can be tested, is not ambiguous, and is dichotomous (a “yes” or “no” statement).

HA: Less than 5 mg/l of chemical “A” in the reservoir water will be lethal to bluegill minnows.

But remember that the prediction could be erroneous. Therefore, a null hypothesis (designated by H0) must also be developed:

H0: Less than 5 mg/l of chemical “A” in the reservoir water will not be lethal to bluegill minnows.

Range of tolerance — In environmental science, we often investigate the relationship between organisms

and the abiotic (non-living or physical) characteristics of the environment, such as temperature, moisture,

nutrient availability, and nutrient toxicity. Most organisms thrive under optimum environmental conditions. There is a small percentage of each species that can survive under less-than-ideal conditions despite being

physiologically stressed. Such organisms will more readily adapt to changing environmental conditions and

thus ensure the survival of the species. Often referred to as the Law of Tolerance, this relationship between population size and environmental condition is reflected in the following figure. This curve may also reflect

the relationship between, for example, numbers of predators and the prey population.

Revised: August 7, 2019 4

Idealized Range of Tolerance Curve

Step 3 – Design an appropriate test/experiment to assess the hypothesis/prediction

A well-designed experiment needs to have an independent variable and a dependent variable. The

independent variable is what the scientist manipulates in the experiment. The dependent variable

responds to the manipulation of the independent variable. Therefore, the dependent variable provides the data for the experiment. Said another way, the independent variable causes a response that is measured as

the dependent variable…. or…the independent variable may be considered as an action that results in a

reaction (dependent variable). Consider, for example, a fire alarm in a building. It is not until the alarm

rings that people will quickly evacuate the building. Therefore, it is the ringing of the alarm this is the independent variable that causes the dependent response of people quickly evacuating the building.

Variables that are held constant are called controlled variables. For example, if we wanted to test the

effects of varying the level of dissolved oxygen on the survival of fish, then we would maintain other

environmental factors (such as temperature, light, availability of food) constant to ensure that they were not affecting whether the fish survived.

A well-designed experiment should distinguish between the treatment (the experimental condition) and

the control (reference for comparison). All variables are held constant for the control. For the treatment,

only the independent variable is changed to determine the consequent outcome (dependent variable). The control is a source of reference and, since no variables are manipulated for the control, then no response or

change should be noted. If the control remains constant, then changes that result from the manipulation of

the independent variable for the treatment are attributed to the experimental factor.

If changes are noted in the control, then such changes are attributed to one or more confounding variables. The difficulty with confounding variables is that they are not readily identified before or during

the study and often leading to misinterpreted or incorrect results.

Step 4 – Conduct test/experiment, record and analyze the results

The data may be qualitative (a verbal description of observed outcomes of the experiment) or quantitative (involving the collection of numerical values that can be mathematically assessed or applied

to a statistical model). Observation must be thorough and impartial. But, be cautious to present your data

in a factual manner. Your interpretations, opinions and conclusions are NOT part of presenting and analyzing the results – they properly belong to Step 5.

Instruments used to collect data should be properly calibrated. Testing equipment and methods should be

consistent throughout the investigation. Multiple tests should be conducted on each test parameter, and the

existence of outliers (unusual values) should be noted. When outliers are observed, the testing methods

and equipment should be checked carefully for malfunctions and recording errors. Finally, all observations

Revised: August 7, 2019 5

must be noted in permanent written documentation so that it can be evaluated later and by others.

Sources of Error – To assess validity of scientific work, sources of error should be identified and evaluated. Common sources of error may result from measurements, testing procedures and human error.

Precision is a measure of the scatter, dispersion, or ability to replicate the measurements. Low-precision (high-scatter) measurements are referred to as noisy data. Smaller average difference between repeat

(replicate) measurements means higher precision. For example, if a sheet of paper is measured several

times with a ruler, we might get measurements such as 10.9, 11.0, 10.9, and 11.1 inches. If a micrometer is

used instead, we might get measurements such as 10.97, 10.96, 10.98, and 10.97 inches. These estimates show random variation regardless of the measuring device, but the micrometer gives a more precise

measurement than does the ruler. If the ruler or micrometer is poorly made, it may yield measurements

that are consistently offset, or systematically biased, from the true lengths. Accuracy is the extent to which the measurements are a reliable estimate of the ‘true’ value. Both random errors and systematic

biases reduce accuracy. To reduce errors of measurement, many measurements may be obtained and then

averaged to attempt to minimize bias and achieve accuracy.

A representative sample is a small subset of the overall population, exhibiting the same characteristics as

that overall population. It is also a prerequisite to valid statistical induction, or quantitative generalization. Representative sampling is essential for successful averaging of random errors and avoidance of

systematic errors, or bias. With random sampling, every specimen of the population should have an equal

chance of being included in the sample. There are standardized techniques for conducting random sampling to obtain a representative sample. Sometimes, however, random sampling is not feasible, and the

results may therefore not be consistent with the overall population and be free of bias.

Presenting and Analyzing Results — Modern science almost always employs a statistical analysis to

interpret data. Reference the Lab 1 background for guidance on selecting appropriate graphic method and mathematical analysis of the data. These interpretations are quantitative in nature and allow the scientist to

determine whether the experimental results indicate a consistent trend or condition.

Interpretations may also be qualitative in nature. For instance, a hypothesis predicted that there was fecal

coliform in a local stream and, after repeated testing, none was found. This could be qualitatively

interpreted that there is an insignificant amount of fecal coliform in the stream. This type of qualitative interpretation leaves room for errors in judgment.

Step 5 – Interpret the results and draw conclusions ➔ accept, revise, or reject the hypothesis

When statistical evaluation of experimental results is conducted, there will either be a statistical difference

between the tested subject and a control group (supports hypothesis HA) or there will be no difference

between the tested subject and the control group (supports null hypothesis H0). Lacking statistical

evaluation requires that the mathematical analysis and/or qualitative outcomes be interpreted to determine

whether the hypothesis is accepted, modified, or rejected.

For example, the determination of an insignificant amount of fecal coliform in a stream could be interpreted as the water is safe to drink. But would you feel safe drinking the stream water?

• Hypothesis Accepted – If the hypothesis is accepted, the student will write a formal report and

contribute this work to the existing scientific literature. The report will make it possible for other scientists (in this case, other students, or the instructor) to evaluate work for scientific soundness

and to repeat the experiment to verify the results. This process is known as peer review.

• Hypothesis Rejected – If the hypothesis is rejected, the student will write a formal report and

contribute this work to the existing scientific literature. Significant knowledge can be gained from ideas that fail. This makes it possible for the original researcher or other students to investigate the

same topic and to build upon the rejected hypothesis from the former investigation. Edison, for

example, did not invent the light bulb. Over a year and a half, Edison significantly improved upon a

fifty-year old idea. In creating an electric lighting system that contained all the elements necessary to make the incandescent light practical, safe, and economical for home use, Edison found 10,000 ways

that would not work.

Revised: August 7, 2019 6

Step 6 – Reporting the results

Results of scientific research must be shared to complete the cycle of the scientific method and stimulate

further thought, allow testing of the methods and results, and ensure the opportunity for potential development from hypothesis to corroborated hypothesis to scientific theory or perhaps even recognition

of a scientific fact or natural law. Several common methods of reporting are used:

◼ Formal memorandum

◼ Formal laboratory reports

◼ Peer reviewed scientific articles

Formal Memorandum

The standard reporting format for many state and federal agencies, as well as in industry, is a formal

memorandum. A longer report format is also common. The formal memorandum follows the following

format. Be sure to indicate the content of each section of the memo by using the respective labels (i.e.,

Label sections as: Background, Investigation, Conclusions and Recommendations).

MEMORANDUM

To: (indicate the name of the receiver – if an agency, also include formal title and agency

name)

From: (indicate your name)

Date: (date memorandum is being submitted)

Subject: (description of the content of the memo, for example: Analysis of fecal coliform content

of Turtle Creek, Dallas County, Texas)

Background: Concise paragraph (or more if needed) to outline:

◼ Where (reference map), when and why the study was conducted

◼ provide general background information on the study area

Investigation: Paragraphs factually outlining and presenting the following:

◼ what tests were conducted

◼ summarize the results and present in table and or graphic form – NOTE: these should be labeled appropriately and referenced in your summary

◼ uncertainties

Conclusions: Concise summary of your interpretations and conclusions, including whether there

is enough evidence to act.

Recommendation(s): Itemize and support your recommendations (for example, what action should be undertaken to respond to the situation or what further action may be

needed to develop enough evidence to support taking actions)

Attachment(s): A list of attached documents (e.g., figures, tables, graphs) that are attached in

order at the end of the memorandum – NOTE: all included figures, tables,

graphs or maps MUST be appropriately referenced and explained in the

document.

Revised: August 7, 2019 7

Formal Laboratory Reports

General Comments: Writing is one of the most important things you will do in the laboratory. All formal

laboratory reports must be typed and submitted in hard copy. Good communication is essential. Therefore, good grammar, correct spelling and word choice, as well as paragraph structure are necessary. Once you

have written your laboratory report, re-read and edit it to develop a well-written document. Make use of

the College Writing Lab to help you edit your written document and improve your writing skills.

Each of the following sections should be included in your report. Each section should begin with the name

of the section in ALL CAPS. You may review “Labwrite” as a resource to help you prepare, organize, interpret and write a formal laboratory report < http://labwrite.ncsu.edu/ >

1. TITLE – Choose a title that describes the hypothesis you are testing. You may want to use the independent variable and the dependent variable in your title (e.g., The Effects of Ozone on

Ultraviolet Radiation).

2. INTRODUCTION – Identify the phenomenon you studied/tested and provide relevant background information (e.g., why are you doing this experiment, what initial observations or

questions led to this line of research and to your specific experiment, what is the environmental

significance?) This discussion will likely include information from other

studies/documents/sources which must be properly referenced and cited.

3. HYPOTHESIS – State the hypothesis that your experiment was designed to test; the hypothesis should be specific, presenting the independent variable and the expected result in the dependent variable. For example: Precipitation with a pH of 3.6 will result in 20 percent lower rates of seed

germination of red maple (Acer rubrum). Presentation of the hypothesis may use the formal IF-

THEN hypothesis statement indicating the expected relationship between the dependent variable and the independent variable (e.g., If there is more ozone in the upper atmosphere, then less

ultraviolet light will reach the surface of the earth.). The hypothesis may reflect a predicted

ranking of results. For example, For brine shrimp exposed to increasing concentrations of three

chemicals, Chemical A will have the lowest LC-50 (most toxic), Chemical B will have the highest LC50 (least toxic), and Chemical C will have intermediate toxicity.

4. MATERIALS AND METHODS – Describe exactly how and when you conducted your experiment. Include enough detail on experimental design, experimental apparatus/equipment, methods of gathering and analyzing data, and types of experimental control so that someone

reading your report could accurately repeat your experiment. Steps should be discussed in

chronological order. Use diagrams or drawings if they would help the reader understand and replicate the experiment (see comments under 5. RESULTS for how to identify such illustrations).

Describe any materials or equipment you used, again with enough detail to enable someone to

repeat your experiment. This section should be written in past tense and active voice as work

completed (e.g., We filled each of three petri dishes with 20 ml of tap water.).

5. RESULTS – Report the results of your experiment. Present your observations / data with NO interpretations or conclusions about what they mean. You must have text in this section,

supported using tables, graphs and/or charts to aid in presenting the results. Include a discussion of uncertainties.

Be sure to make specific reference to all such tables, graphs, photographs, drawings, diagrams,

maps, etc. Also report the results of any statistical tests. All tables or other types of illustrations

should be numbered (in the order in which they are referenced in the text and should have an appropriate title. Tables are identified above the table. All other illustrations are referred to as

figures and are captioned beneath the illustration. This section should be written in past tense as

work completed.

Include in a table every data point you collected in your experiments, unless you collected

more than 100 data points. If there were more than 100 data points, you may save space and report

only the number of points and the relevant averages or means.

Revised: August 7, 2019 8

6. DISCUSSION – Explain what your data and results mean. Describe patterns and relationships that emerged. Explain how any changes to or problems with the experimental design/procedure may have affected the results. Consider the following questions: is it conclusive as a test of your

hypothesis? Discuss possible sources of error in your experiment? Does the experiment need to be

repeated before drawing conclusions about your hypothesis? How do your results compare with

the results of previous research on the same subject? What further questions do the results of your experiment raise? What experiment(s) should be done next?

7. CONCLUSION – Briefly summarize what you did, why you did it, and what happened. This should include a brief statement indicating whether your hypothesis was supported or not supported. If appropriate, propose a modified hypothesis.

8. LITERATURE CITED – Alphabetical list of books, publications, documents, or web sites you refer to that support statements you make in your report. In the body of the report, in-text

referencing to these sources is given by giving the author and year of publication within parentheses at the end of the sentence which includes the cited information.

• In the reference citations, for a website, be sure to give the COMPLETE URL for the webpage (do NOT just list the main website) from which you obtained your

information!!! DO NOT put the URL in the in-text reference. For example, the information that “17,694 generators produced 30 million tons of hazardous waste in the

United States” is derived from the U.S. Environmental Protection Agency but it will NOT

be found at: http://www.epa.gov/ and this main EPA website should NOT be cited as the source. Rather, the statistic is found at: http://www.epa.gov/epaoswer/osw/tsds.htm and

this is the complete URL that should be included in your reference citation.

Examples are provided below for the format you should use in the actual alphabetical list of all literature cited.

BOOK:

Junger, S. 1997. The Perfect Storm. HarperCollins, New York. 301pp. (list specific pages or a chapter if you

only used the book to refer to specific information on a few pages, eg., if we were listing this book only for its reference to the tragedy of the commons and the swordfish fishery, we might add “see p. 83-84”)

CHAPTER IN EDITED BOOK WITH DIFFERENT AUTHOR FOR EACH CHAPTER:

Miller, J.E. 1988. Effects on photosynthesis, carbon allocation, and plant growth associated with air pollutant

stress. Pages 287-316 in Heck, W.W., O.C. Taylor, and D.T. Tingey (eds.), Assessment of Crop Loss

from Air Pollutants. Elsevier Applied Science, New York. 552pp.

ARTICLE IN MAGAZINE OR JOURNAL:

DuBay, D.T. 1996. Work your plan, plan your work: North Carolina’s Environmental Education Plan. Friend

of Wildlife – The Journal of the North Carolina Wildlife Federation 44(3):10-11. (Summer 1996)

Ehrlich P.R., Murphy D.D., M. C. Singer, M.C., Sherwood, C.B., White, R.R. and Brown, I.L. 1980.

Extinction, reduction, stability and increase: The responses of checkerspot butterfly (Euphydryas) populations to the California drought. Oecologia 46(1): 101-105. (July 1980

INTERNET WEB SITE (Citations for Internet websites should be like print media citations, including

author or sponsoring agency, publication date, article title, site title, URL, the date the information was

posted, and the date when the web address was accessed to obtain the information.):

North Carolina State University. 2004. Labwrite for Students – Improving Lab Reports. Sponsored and

funded by National Science Foundation. http://labwrite.ncsu.edu/index.html

Plaisance, S. 2006. Wasps Released in Louisiana to Combat Bugs. Environmental News Network, Inc., San Francisco. < http://www.enn.com/today.html?id=11430 > posted October 12, 2006, accessed November