Scientific Method
What is a variable?
A variable is anything that can change in an experiment.
What is an independent variable (IV)?
An independent variable is something that a scientist changes during an experiment. Example: I want to know if exercise causes weight loss, so I ask one group to exercise every day and another group not to exercise at all. Since the amount of exercise is changed, it's an independent variable. Exception: Whenever the changes in a variable are measured over time, time is generally considered to be the independent variable even though we cannot change time.
In most experiments, should scientists study the effects of many variables at once or just a few?
Only a few because the scientist's goal is to keep things the same as much as possible except for one or two independent variables. In this way, the scientist can be relatively sure that whatever caused a change in the outcome variable had something to do with the independent variables being changed.
What is an experimental group?
The experimental group undergoes the experiment. So if you want to know if exercise causes weight loss, the experimental group would exercise. If you wanted to know if a drug cures cancer, then the experimental group would take the drug.
What is a control group?
A control group doesn't undergo the experiment. So if you want to know if exercise causes weight loss, the control group won't exercise. If you wanted to know if a drug cures cancer, then the control group won't receive the drug.
Why is it important to have a control group?
A control group gives a scientist baseline measures for comparison.
What is a dependent variable (DV)?
A dependent variable is an outcome variable. Example: If I want to know whether exercise causes weight loss, then since weight gain or loss is the outcome, it's the dependent variable. It *depends* on something that happened earlier in the study.
What is a hypothesis?
A hypothesis is an educated guess.
What are data?
Facts, figures, and other evidence gathered through observations. Note: Data is a plural word. There is no singular form in the United States. (The UK uses "datum").
What are the 3 rules for making an hypothesis?
They are 1) it must be an EDUCATED GUESS 2) About something that can be measured 3) It must be written BEFORE you do any testing.
What are the 6 steps of the Scientific Method?
They are to 1) Pose Questions 2) Develop a Hypothesis 3) Design an Experiment 4) Collect Data 5) Draw Conclusions and 6) Share/Communicate your findings.
What are the 3 skills that scientists need?
To predict, observe, and infer.