Friday, 30 August 2013

Multiple datasets test for SciStatCalc 1.3

The following statistical tests require more than 2 datasets, which need to be entered in the left box:-
  1. Bartlett's test
  2. Kruskal-Wallis test
  3. One-way ANOVA test
  4. Two-factor ANOVA test
The method of entering data is by separating each dataset by a semi-colon - each dataset is made up of comma separated numbers.

Consider the one-way ANOVA example in http://cba.ualr.edu/smartstat/topics/anova/example.pdf, where the following results are shown:-

Suppose the National Transportation Safety Board (NTSB) wants to examine the safety of compact cars, midsize cars, and full-size cars. It collects a sample of three for each of the treatments (cars types). Using the hypothetical data provided below, test whether the mean pressure applied to the driver’s head during a crash test is equal for each types of car. 

Table ANOVA.1
Compact cars  Midsize cars Full-size cars

643                  469              484 
655                  427              456 
702                  525              402

The above data should be entered in the One-way ANOVA test panel as shown:-


one-way ANOVA

Pressing the calculate button results in a full breakdown of the results for the ANOVA test that populates the right (textview) box as well as post-hoc analysis should the results be significant, and is best illustrated by the video on youtube accessible at:-

The post-hoc analysis is based on the Tukey's HSD test, and is restricted to the scenario where all the populations have the same number of samples.

The above datasets can be input as a CSV file attachment - the file should have contents as below:-

# 3
643,469,484 
655,427,456 
702,525,402

Note that the first line is a comment line, starting with the character # and followed by number 3, which is the number of groups/datasets/populations. Also, each column of the CSV file corresponds to a particular group/dataset - this restricts all the groups/datasets to have the same number of samples, for file import mode.