The Process of Science: Scientific Method and Experimental Design

The Process of Science

Definition of Science

Science is a systematic approach to understanding the natural world through observation and experimentation. It is an evidence-based process that evolves with new discoveries.

• Science means "to know" and involves drawing conclusions based on evidence.

• Scientific knowledge is provisional and subject to change as new evidence emerges.

Steps in the Scientific Method

Overview of the Scientific Method

The scientific method is a logical sequence of steps used to investigate natural phenomena and answer questions.

1. Make an Observation: Notice something in the natural world.

2. Ask a Question: Formulate a question based on the observation.

3. Form a Hypothesis: Propose a tentative explanation (hypothesis) for the observation.

   • Must be testable (can be investigated through experiments or observations).

   • Must be falsifiable (can be proven false by evidence).

4. Set Up the Test/Experiment: Design an experiment to test the hypothesis.

   • Use two groups:

     • Control Group: Used for comparison; may receive a placebo.

     • Experimental Group: Receives the variable being tested.

   • Identify variables:

     • Independent Variable: The factor that is changed or manipulated (e.g., caffeinated coffee).

     • Dependent Variable: The outcome measured, which depends on the independent variable (e.g., memory test scores).

5. Collect Results/Data: Gather and analyze data from the experiment.

   • Qualitative Data: Descriptive, non-numerical results (e.g., positive/negative test results, high/normal cholesterol).

   • Quantitative Data: Numerical measurements (e.g., 1600 units vs. 0 units, 350 mg cholesterol vs. 150 mg).

6. Draw Conclusions: Decide whether the data support or falsify the hypothesis. If falsified, revise the hypothesis and repeat the process.

Example: Does Caffeinated Coffee Boost Memory in the Elderly?

• Anecdotal Evidence: Many believe caffeine increases alertness, but this is not scientifically tested.

• Observation: Memory test scores in the elderly decline in the afternoon.

• Question: Does consuming caffeinated coffee before an afternoon memory test improve scores?

• Hypothesis: Consuming caffeinated coffee prior to memory testing will boost memory scores in the elderly.

• Experiment:

  • Participants: Elderly individuals (65+), equal males and females.

  • All took memory tests in the morning and afternoon.

  • Control group received decaf coffee (placebo); experimental group received caffeinated coffee before the afternoon test.

  • Memory test scores (dependent variable) were compared between groups.

• Results: Control group’s scores declined in the afternoon; experimental group’s scores remained similar to morning scores.

• Conclusion: The hypothesis was supported—caffeinated coffee boosted memory in the elderly.

Sample Size and Replication

Importance of Sample Size

• A larger sample size increases the statistical significance of results, reducing the impact of random variation.

• Replication refers to repeating experiments to confirm findings. Peer researchers often replicate studies to verify results.

Scientific Theory and Epidemiology

Definitions

• Scientific Theory: A hypothesis that has been repeatedly tested and consistently supported by evidence. It is broader and more comprehensive than a hypothesis.

• Epidemiology: The study of patterns of disease in populations and the factors that influence their distribution.

Correlation vs. Causation

Understanding Relationships

• Correlation: When two variables change together, but one does not necessarily cause the other.

• Causation: When one variable directly affects another.

• Example: Increased department store sales in winter months are correlated with the season, but the true cause is likely holiday shopping, not cold weather.

Additional info: Scientists use controlled experiments and statistical analysis to distinguish between correlation and causation, avoiding incorrect conclusions about cause-and-effect relationships.