Research Methods Quiz 2: Data Issues and Null Hypothesis Testing

Nominal (data)

discrete categories

Ordinal (data)

relative amounts

Interval (data)

actual amounts without ‘0’

Ratio (data)

actual amounts with ‘0’

3 Measures of Central Tendency (M,M,M)

1. Mean

2. Median

3. Mode

2 Measures of Dispersion

1. Range

2. Standard Deviation

3 Measures of Effect Size (ES,d,r)

1. eta-squared

2. Cohen’s d

3. r

Eta-squared Effect Size (small, medium, large) (values)

1. small = .01

2. medium = .06

3. large = .14

F, r, p, and eta-squared with increased sample size

F = increases

r = no change

p = decreases

eta-squared = no change

Descriptive Statistics (definition)

summarize the data from a sample

Inferential Statistics (definition)

generalize the sample results to the population

Sample (purpose)

to represent a population so sample results can be inferred to the population

What does “statistically significant” mean?

means that you are sure, beyond a reasonable doubt, that the difference you observed is not a fluke

What does “p<.05” mean?

probability is less than 5% that you would get a result this extreme by chance if the null hypothesis were true

3 Caveats Regarding Statistical Significance Effects

1. not necessarily large effects

2. may have no practical significance

3. may not be in expected direction

4 Components of a Null Hypothesis

1. no effect

2. type of relationship/mean difference

3. specifies the variables

4. specifies the population and sample

4 Components of a Research Hypothesis

1. type of relationship/mean difference

2. direction/pattern (+/-; pattern of means)

3. specifies the variables

4. specifies the population and sample

3 Outcomes for Statistical Analysis

1. retain the null

2. reject the null AND pattern/direction matches research hypothesis

3. reject the null AND pattern/direction does not match research hypothesis