L3 Scientific Investigation

Variable

Any condition that changes or varies the outcome of a scientific inquiry

dependent variable

changes in the response to change in the independent variable

Independent variable

A variable that is changed by the scientist in the experiment

constants

Scientists try and “control” for everything else (keep the same)

Control variable

variable where no manipulation is done

Control variable purpose

A comparison to the actual experimental groups to see if the expriment really makes a difference

3 types of scientific inquiry

1. Controlled experiment

2. Observational study

3. Correlational study

Purpose of controlled experiment

To determine wether one variable causes an effect on another variable

How is controlled experiment conducted

The scientists make controlled changes to the independent variable to see its affect on the dependent

Controlled experiment example

Change in temperature (independent) to see how it affects chemical reaction(dependent)

Control variable in a controlled experiment

No independent variable is given, but you still measure the dependent variable in order to see how the experimental groups compare

Control variable example

Same chemical reaction is run with no temp changes

Observational study purpose

Scientists use this to gather formation about a natural phenomenon

How an observational study works

Simply observe a subject without influencing it

Observational study example

In ecology to determine the climate changes or in astronomy looking at stars

Correlational study

• Used to determine wether 1 variable is affecting another

• Without controlling any of the variables

• Observe variables naturally

Positive correlation

Increase in one variable corresponds to an increase in the other

Negative correlation

Increase in one variable corresponds to a decrease in the other

No correlation

No pattern in the graph