# Choosing a Statistical Measure Parametric vs. Non-Parametric

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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