Changelog

Below you can find our record of all notable changes made to the Statkat website. Note that the website is currently running in Beta mode. Please send us any comments/feedback/bugs via our contact form. Thank you!

### Statkat Version 2.5 Beta - Feb 22, 2018 - updates

- Three questions added about the one sample $z$ test for the mean. Total number of practice questions in the database = 158.

### Statkat Version 2.4 Beta - Feb 7, 2018 - updates

- Extra practice material added (new category): drag & drop questions
- Three questions added about the one sample $z$ test for the mean. Total number of practice questions in the database = 155.
- Table added to several overview tables, that explains how to find critical $z$ value

### Statkat Version 2.3 Beta - Feb 2, 2018 - updates

- Two questions added about chi-squared test for the relationship between two categorical variables. Two questions added for the one sample $t$ test. Total number of practice questions in the database = 152.

### Statkat Version 2.2 Beta - Jan 25, 2018 - updates

- Three questions added about chi-squared test for the relationship between two categorical variables. Total number of practice questions in the database = 148.
- Bug fixed for question 4 Kruskal-Wallis test: answer options are now all unique.

### Statkat Version 2.1 Beta - Jan 18, 2018 - updates

- One question added about code variables. One question added about the ANOVA $F$ test. Three questions added about the $z$ test for a single proportion. Total number of practice questions in the database = 145.
- Explanation for question 1 about sum of squares in regression improved.

### Statkat Version 2.0 Beta - Jan 11, 2018 - updates

- New feature added: test selection tool.
- One question added about the $z$ test for the difference between two proportions. Total number of practice questions in the database = 140.

### Statkat Version 1.12 Beta - Nov 28, 2017 - updates

- One question added about moderator analysis. One question added about partial and semi-partial correlation. Two questions added about classification tables in logistic regression. Total number of practice questions in the database = 139.

### Statkat Version 1.11 Beta - Nov 17, 2017 - updates

- Three questions added about $R^2$. One question added about moderator analysis. Total number of practice questions in the database = 135.

### Statkat Version 1.10 Beta - Nov 10, 2017 - updates

- Two questions added about multicollinearity. One question added about outliers and influential points. Total number of practice questions in the database = 131.

### Statkat Version 1.9 Beta - Nov 04, 2017 - updates

- Two questions added about multicollinearity. Two questions added about $R^2$. Total number of practice questions in the database = 128.

### Statkat Version 1.8 Beta - Oct 26, 2017 - updates

- Two questions added about contrasts. Two questions added about multiple comparisons. Total number of practice questions in the database = 124.

### Statkat Version 1.7 Beta - Oct 19, 2017 - updates

- Two questions added about two way ANOVA table. Two questions added about the interpretation of regression coefficients in a simple regression equation. One question added about the interpretation of the Pearson correlation coefficient. Total number of practice questions in the database = 120.
- ANOVA table added to overview two way ANOVA

### Statkat Version 1.6 Beta - Oct 16, 2017 - updates

- Question added for one way ANOVA about finding $F$ value and critical value $F^*$, three questions added for regression analysis (OLS) about outlier types. Total number of practice questions in the database = 115.
- Better formulation of null and alternative hypothesis of $\chi^2$ test

### Statkat Version 1.5 Beta - Oct 3, 2017 - updates

- Question added for one way ANOVA about interpretation of the $p$ value, question added for Correlation about the critical $t$ value

### Statkat Version 1.4 Beta - Sep 28, 2017 - updates

- Question 1 in Tests and confidence intervals for regression coefficients now uses SPSS table
- Three questions added for Tests and confidence intervals for regression coefficients. Total number of practice questions in the database = 109
- Two sample $t$ test and pooled two sample $t$ test are now called two sample $t$ test: equal variances not assumed and two sample $t$ test: equal variances assumed

### Statkat Version 1.3 Beta - Sep 21, 2017 - updates

- 2 questions added about effect sizes within one way ANOVA, 2 questions added about effect sizes within two way ANOVA, 1 question added about significance testing for the pearson correlation coefficient. Total number of practice questions in the database = 106

### Statkat Version 1.2 Beta - Sep 15, 2017 - updates

- Question SE of the mean within one way ANOVA added. Total number of practice questions in the database = 101
- Better description of Stein's $R^2$ in overview table for OLS regression
- Formulation of several questions improved

### Statkat Version 1.1 Beta - Sep 10, 2017 - updates

- 2 questions added. Total number of practice questions in the database = 100
- Links to practice and overview areas fixed on the homepage
- User feedback buttons added in practice area
- Button jQuery functionality seperated from the interface for Android compatibility