Understanding the Scientific Method and Hypothesis Formation

Scientific method

a step-by-step process used by scientists to investigate questions, gather evidence, and draw conclusions based on experiments and observations.

Hypothesis

predictions that can be tested by recording more observations or experiments.

Null hypothesis (H0)

a hypothesis which the researcher attempts to disprove, reject or nullify; by attempting to reject the null, researchers can support their experimental hypothesis and draw meaningful conclusions.

Alternative hypotheses

hypotheses that are listed after the null hypothesis, starting with H1 and continuing as necessary for the experiment.

Example null hypothesis statement

H0: There will be no difference in headache relief between individuals who take Tylenol and those who do not.

Example alternative hypothesis H1

Tylenol will allow for relief when consumed by patients with headaches.

Example alternative hypothesis H2

Tylenol will worsen symptoms when consumed by patients with headaches.

Observation

the act of noticing and describing events or processes in a careful, orderly way.

Question

a statement that seeks to gather information or clarify a concept.

Experiment

a procedure carried out to support, refute, or validate a hypothesis.

Data

facts and statistics collected together for reference or analysis.

Conclusion

a summary of the results of an experiment, indicating whether the hypothesis was supported or refuted.

Manipulated variable

the variable that is changed or controlled in a scientific experiment.

Responding variable

the variable that is measured in an experiment.

Significant results

results that indicate a meaningful difference or effect, rather than one due to chance.

Chance

the occurrence of events without any apparent reason or cause.

Step 1 of Scientific Method

Make an observation.

Step 2 of Scientific Method

Ask a question.

Step 3 of Scientific Method

Propose a hypothesis.

Step 4 of Scientific Method

Design an experiment.

Step 5 of Scientific Method

Collect data.

Step 6 of Scientific Method

Draw a conclusion.

Control

Used for comparison to the experimental group

Experimental

Receives the experimental treatment (IV) being tested to observe its impact on the outcome (DV)

Negative

Group NOT exposed to any treatment OR exposed to a treatment known to have NO effect

Positive

Group not exposed to the IV but IS exposed to a treatment known to HAVE an expected effect

Independent

The one factor that is changed between groups; what is being manipulated; graphed on the x-axis

Dependent

Factor that is measured and affected by the IV; graphed on the y-axis

Constant

Factors kept consistent for all groups to ensure only the IV affects the outcome; aka controlled variables

Negative control

treatment that is known to have no effect

Positive control

Use an established antibiotic that is known to work

Independent variable

the amount of cars you wash

Dependent variable

the amount of money you receive

Independent variable

physical stress exposure

Dependent variable

heart rates

Negative control

placebo pill (or substance that has no effect)

Positive control

Test subjects are given a drug that is known to reduce blood pressure.

Negative control

water

Positive control

energy drink

bias

a prejudice in favor of or against something

Control

Ensures the experimental setup can produce a known effect; provides a reference point for what a known effect looks like

Negative

Helps to ensure there is NO effect when there should be NO effect

Experimental

help to validate statistical analysis and increase confidence in conclusions drawn from the experimental results

Adults may be able to solve geometry problems better than teenagers

H1:

Adults will solve more problems than teenagers

If teenagers and adults are given geometry problems to solve, then adults will solve more problems than teenagers (because they are older and have more experience doing problems)