1. What is Experimental Research?

2. Experimental research is…
The manipulation and control of variables

3. Speaking of variables….

4. What are the two types of variables?
Independent variables
Dependent variables

5. Independent variables are…
What is being tested?
What is being changed on purpose?

6. Dependent variables are…
What is being observed?
What is being measured?
The data
The ‘effect’ caused by the independent variable

7. “Constants” are… Variables that could change, but don’t
Must be kept constant by the scientist
Allow for a “fair test”

8. So an experimental question has to indicate the variables
How the independent variable will AFFECT the dependent variable
What the EFFECT of the independent variable will have on the dependent variable

9. For example…
How does the temperature of ocean water affect the speed of a hurricane?
Independent variable
Temp of ocean water
Dependent variable
Speed of a hurricane

10. Hypothesis
Educated guess about what will happen during an investigation
Based on prior knowledge (observations, background research, etc)

11. Hypothesis (plural – hypotheses)
Special kind of prediction
What makes it so special???
It’s a guess about the VARIABLES & their relationship, in particular,
How will the independent variable affect the dependent variable?????????

12. How to write a hypothesis
Use an If -- Then statement
IF the independent variable changes, THEN the dependent variable changes
This type of sentence shows what the IV will do to the DV

13. For example…
IF the Temp of ocean water increases, THEN the speed of a hurricane will increase.
This shows the expected relationship between the independent variable (the T of ocean water) and the dependent variable (the speed of a hurricane)
If the T of ocean water changes, it will cause the speed of a hurricane to change too.

14. Planning the investigation – Experimental Design
You absolutely, positively have to know what the variables are!
What you are changing
How you are changing
What you are measuring
How you are measuring
Repeated trials
Data tables

15. Data tables?
Numerical (quantitative) data organized in rows and columns
The specific independent variables are listed
The number of trials are listed
Blanks are left for the data (dependent variable) to be filled in

16. Title Describing the Data
Trial
Variable 1
Variable 2
Variable 3 1 2 3 4 5
Average

17. Analyzing the data Reduce the data
Do something to make the amount of data smaller
Central tendencies
Mean (average)
Median
Mode
Range
frequency

18. Analyzing the data Graph the data
Lets us see trends, patterns, relationships, comparisons
Bar graphs
Let us compare data
Line graphs
Lets us see trends or changes

19. This shows a comparison of types and amount of trash on a beach.
Bar graph
This shows a comparison of types and amount of trash on a beach.

20. Line graph
This shows how the grade point average has been changing over several years. The trend is an increase in GPA.

21. Draw a Conclusion How we sum up the investigation
Does the data support the hypothesis?
If it does – we accept the hypothesis
If it does not – we reject the hypothesis
All back up what you say with data
Evidence
Discuss issues or problems with the investigation
Discuss the importance or relevance of the investigation

22. Communicate/Share Results
Finding out something new doesn’t do anyone any good unless the new knowledge is shared
Journals & magazines
Presentations