Null effects in research designs

state abelson’s laws about null effects

1. chance is lumpy

2. overconfidence abhors uncertainty

3. there is no free hunch’

4. you can’t see the dust if you don’t move the couch

5. criticism is the mother of methodology

what are the criteria for failing to reject the null

1. must be falsifiable, possible

2. results mut be consistent with null

3. experiment made a concerted effort to find an effect

define manipulation checks

addition of a dependent variable included to ensure the independent variable worked

what are the 3 possible causes of null-effects in within-groups designs

1. measurement error

2. individual differences

3. situation noise

define situational noise

external distraction which could cause variability within groups obscuring between or within groups differences