Independent Variables
This variable is the variable that the scientist changes on purpose
The independent variable
The variable that the scientist measures is the...
Dependent variable
This is an if... then... statement that is sometimes referred to as an "educated guess". It is always testable.
A hypothesis.
How many variables should be CHANGED in a well designed experiment?
1
What is a placebo?
Experiment: Are test scores impacted by the amount of sleep a student gets the night before a test?
Independent variable is:
The amount of sleep the student gets
Experiment: Are test scores impacted by the amount of sleep the student gets the night before the test?
What is the dependent variable?
The test scores
These variables always remain the same in an experiment.
Controlled variables.
What is the purpose of the control group?
It serves as a comparison for the experimental groups.
What is bias and how can scientists avoid it?
Bias is predisposition to one outcome or another. It can be avoided by blinded experiments, double blinded experiment, use of placebos, and random sampling.
Experiment: Teacher wants to see how caffeine impacts test scores.
Independent variable is:
Amount of caffeine
Experiment: Teacher wants to know if caffeine impacts a students test scores.
What is the dependent variable?
Test scores
The control group.
Why is it important that the experiment controls all the variables except one?
So that scientists know which variable impacted the dependent variable.
What do you call a well-established explanation of a natural phenomenon that has been repeatedly confirmed through experimentation?
A scientific theory
Experiment: Drug manufacturers are testing a medication for depression. They give one group a placebo, one group 10mg daily, another group 20 mg daily, and the last group 30mg daily. The people take a survey about their depression at the beginning of the month and again at the end.
What is the independent variable?
The amount of medication.
Experiment: A scientist wants to know if the amount of sunlight a plant gets impacts the plants health.
Dependent variable?
Health of the plant
a conclusion reached on the basis of evidence and reasoning.
An inference
Why do scientists publish their data and findings?
Answers may vary- to verify their data, to certify that it is up to the standards of the scientific community
A _______________ explains why a phenomenon occurs, while a ____________ describes what happens.
Scientific theory, scientific law
A scientist wants to know if caffeine has an impact on the memory of bees.
What is the independent variable?
The amount of caffeine
Is the dependent variable the CAUSE or the EFFECT?
The effect
a type of statistical hypothesis that proposes that no statistical significance exists in a set of given observations.
The Null Hypothesis
What is the purpose of a hypotheisis in an experiment?
To make predictions that can be tested
How do you minimize the influence of pre-existing differences among subjects?
Random sampling