Choosing a Statistical Measure Parametric vs. Non-Parametric

1. Parametric

1.1. Definition

1.1.1. Inferential statistic concerned with population parameters

1.2. Assumptions

1.2.1. Levels of measurement

1.2.1.1. interval

1.2.1.2. ratio

1.2.2. Distribution

1.2.2.1. normal

1.2.3. Variance

1.2.3.1. equal between population variables

1.3. Most Familiar

1.3.1. t test

1.3.2. F test

1.3.3. Pearson's r

2. NonParametric

2.1. Definition

2.1.1. Inferential statistic not concered with pop parameters

2.2. No Assumptions

2.2.1. as to Levels of Measurement

2.2.1.1. ordinal

2.2.1.2. nominal

2.2.2. as to Distribution

2.2.2.1. can use small sample size

2.2.3. as to Variance

2.3. Scores

2.3.1. Often converted to Ranks

2.3.1.1. outliers little impact

2.4. Most Familiar

2.4.1. Spearman's r

2.4.2. Chi-Square Test

2.4.3. Wilcoxen Test

2.4.4. Sign Test

2.4.5. Friedman one-way ANOVA by Ranks