BACE Sci Method & Variables

Scientific Method &
Experimental Variables

Scientific MEthod

A reasonably organized way to figure stuff out.

May involve observations and/or experimentation.

Can be done in the field or in the lab.

Should be rooted in empirical evidence and logic.

Data

Empirical evidence generated by scientific endeavors.

Can be qualitative or quantitative.

Usually analyzed for patterns and significance via statistics.

Displayed as graphs, charts, photos, diagrams, maps, etc.

Observational Science

Usually precedes experimentation.
Generates data.
Data can be analyzed for patterns.
Ideally, this process generates scientific questions.

Experimental Science

Designed to study the effects of one or more variables on a system.
Probably addresses a scientific question.
Generates data for analysis.
Must involve careful planning and controls.
Ideally, adds to a body of evidence and generates even more scientific questions.

Data that is recorded.
Depends on which version or level of independent variable is present.
Changes according to independent variable.

Dependent

I set this up.
The variable you are setting at different levels or versions.
The thing you want to see the effect of.

Independent

Experimental Variables

Components of an experiment that are kept uniform among all setups, treatments, or groups.
aka constants

Controlled

Experimental Variables

**Do not confuse these with control groups. Similar concept but different in practice.

Multiple Choice

The variable that is being measured

• independent variable

• dependent variable

• controlled variable (constants)

Multiple Choice

The variable that is kept the same to make sure any/all results are cause by the independent variable.

• independent variable

• dependent variable

• controlled variable (constants)

Multiple Choice

A student is planning an experiment to find out how the height from which they drop a ball affects how high the ball bounces. What is the dependent variable?

• The height that the ball bounces

• Height from which the ball is dropped

Multiple Choice

A student is planning an experiment to find out how the height from which they drop a ball affects how high the ball bounces. What is (hopefully) a controlled variable in this experiment?

• The ball used

• The height the ball bounces

• Height of the ball being dropped

Multiple Choice

What is the Independent Variable (IV) in the following testable question: Does the temperature of a tennis ball affect the height of its bounce?

• the temperature of tennis ball
• height of the bounce

Multiple Choice

What is the Dependent Variable (DV) in the following testable question? Does a metal baseball bat vibrate more than a wooden baseball bat?

• the type of baseball bat
• the amount of vibration

Hypotheses

​Predictions!

Null Hypothesis: The outcome if the independent variable has no impact on the dependent variable.

Alternative hypothesis: The predicted outcome if the IV does have an impact on the DV.

Multiple Choice

Mr. Krabbs wants to make a new secret sauce for the krabby patty that decreases the amount of gas people get. He recruits 200 customers. He gives 100 people in Group A a krabby patty with a mixture of ketchup and mayonaisse which he's always used. He gives 100 people in Group B a new secret sauce that he thinks will help with gas. What is the null hypothesis?

• Group A will have less gas

• Group B will have less gas

• Neither group will experience a difference

Control GRoups

Experimental groups that do not receive any treatment or variation of the IV.
Sometimes they get the "standard" version of IV, if applicable.
In clinical trials, may get a placebo.

Multiple Choice

Mr. Smith thinks that a special juice will increase the productivity of workers. He creates two groups of 50 workers each and assigns each group the same task of stapling a set of papers together. Group A is given the special juice to drink while they work. Group B is not given the special juice. After an hour, Smithers counts how many stacks of papers each group has made. Group A made 1,587 stacks, Group B made 2,113 stacks. Which is the control group?

• Group A

• Group B

• Neither

Tell Ms. Smith about your projects