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Class Notes

NOTES

Steps of the Scientific Method

1. State the problem: What is the problem? This is typically stated in a question format.

? EXAMPLE: Will taking one aspirin per day for 60 days decrease blood pressure in

females ages 12-14?

2. Research the problem: The researcher will typically gather information on the problem. They

may read accounts and journals on the subject, or be involved in communications with other

scientists.

? EXAMPLE: Some people relate stories to doctors that they feel relief from high blood

pressure after taking one aspirin per day. The idea is not scientific if it is untested or if

one person reports this (called anecdotal evidence).

3. Form a probable solution, or hypothesis, to your problem: Make an educated guess as to what

will solve the problem. Ideally this should be written in an if-then format.

? EXAMPLE: If a female aged 12-14 takes one aspirin per day for 60 days, then her

blood pressure will decrease.

4. Test your hypothesis: Do an experiment.

? EXAMPLE: Test 100 females, ages 12-14, to see if taking one aspirin a day for 60 days

lowers blood pressure in those females.

Independent Variable (I.V.): The variable you change, on purpose,

in the experiment. To help students remember it, suggest the phrase

I change it” emphasizing the Independent variable.

EXAMPLE: In this described experiment, taking an aspirin

or not would be the independent variable. This is what the

experimenter changes between his groups in the experiment.

Dependent Variable (D.V.): The response to the I.V.

EXAMPLE: The blood pressure of the individuals in the

experiment, which may change from the administration of aspirin.

Control: The group, or experimental subject, which does not

receive the I.V.

EXAMPLE: The group of females that does not get the dose

of aspirin.

Constants: Conditions that remain the same in the experiment.

EXAMPLE: In this scenario some probable constants would

include: only females were used, only females around the same

age, the same dosage of aspirin was given to all the individuals in

the experimental group for the same defined time interval—60

days, the same brand of aspirin was given, the same type of diet

was ideally given to the members of both groups as well as the

same activity level prescribed.

5. Recording and analyzing the data: What sort of results did you get? Data is typically

organized into data tables. The data is then graphed for ease of understanding and visual

appeal.

? EXAMPLE: Out of 100 females, ages 12-14 yrs., 76 had lower blood pressure readings

after taking one aspirin per day for 60 days.

6. Stating a conclusion: What does all the data mean? Is your hypothesis supported?

? EXAMPLE: The data shows that taking one aspirin per day for 60 days decreases

blood pressure in 76% of the tested females ages 12-14 compared to a decrease in

blood pressure in 11% of the control group. Therefore, the original hypothesis has

been supported, that taking one aspirin per day can decrease blood pressure.

7. Repeating the work: Arguably, the most important part of scientific inquiry! When an

experiment can be repeated and the same results obtained by different experimenters, that

experiment is validated.

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