6. Categorical Data and Nonparametric Statistics Flashcards
Non-parametric tests are used when
The assumptions of parametric tests have not been met.
- Non-parametric tests make fewer assumptions than parametric tests
With 2 2 contingency tables (i.e., two categorical variables both with two categories) no expected values should be below ____.
5
What variables can chi-square be used on?
categorical variables only
When conducting a loglinear analysis, if our model is a good fit of the data then the goodness-of-fit statistic for the final model should be:
Non-significant (p should be bigger than .05)
- If our model is a good fit of the data then the observed and expected frequencies should be very similar (i.e., not significantly different)
What is the parametric equivalent of the Wilcoxon signed-rank test?
The paired samples t-test
What is the parametric equivalent to Spearman’s rho correlation?
Pearson’s r
Are directional hypotheses possible with chi-square?
Yes, but only when you have a 2 × 2 design
- Directional alternative hypotheses using the chi-square test are only valid for 2 × 2 contingency tables – any larger and the chi-square test is testing compound hypotheses
What is the Jonckheere–Terpstra test used for?
To test for an ordered pattern to the medians of the groups you’re comparing.
The _______ test is based on calculating the difference between two sets of scores, making a note of the sign of the difference (positive or negative) and then ranking the differences from lowest to highest ignoring whether they are positive or negative.
Wilcoxon signed-rank test
Chi squared test shows us
- How far away from our expected distribution our observed data is
- How likely (p) any difference between distributions is due to chance Ho
- Then we can say if any difference is significant or not at our alpha level
