Single Variable Experiments

Question 1

Experimental Hypothesis

Answer 1

Prediction the IV will cause a particular effect in DV

• p<.05
• Experiment attempts to support, so that null can be rejected (otherwise fail to reject null)

Question 2

Null Hypothesis

Answer 2

IV has not effect on DV

• p>.05
• can never be proven, can only fail to be rejected
• certain relationship can be missed when only 2 levels

Question 3

Multi-level IVs

Answer 3

1. More likely to show TRUE relationship between IV and DV
2. Allow use of more than one control group (empty control- absent of any treatment- and placebo control- pseudo-treatment)
3. Floor and ceiling effects less likely
4. More economical than a series of two level experiments
5. Allows for all comparisons to be made between levels

Question 4

Floor and Ceiling effects

Answer 4

Regardless of condition:

Floor- DV cannot get any lower
Ceiling- DV cannot get any higher

To avoid, use more than one level of IV (more levels, more likely to have a range of performances)