Sunday, 15 December 2013

Chi-squared test for independence Calculator

Please click to add a row.

This blog post implements an online calculator for Pearson's Chi-squared test for independence. For a discussion on this test, you can have a look here.

Simply click on the link near the top to add text boxes. Each text box stores a single row of data and needs to be filled in with comma separated numbers. All rows need to have the same number of samples, which is equal to the number of columns.

Alternatively, you can choose two file entry methods:-

  1. Select multiple single column CSV files to populate the text boxes by repeatedly pressing the Choose File button - there must be one distinct (and differently named) file for each text box i.e. one file per group. Each file can have a different number of samples.
  2. Select a single multi-column CSV file by pressing the Choose File button once, where the number of columns equals the number of groups - all groups need to have the same number of samples.

In addition, a table of standardised residuals is calculated. A negative value of a particular element means that the observed frequency is lower than the expected frequency, whereas a positive value implies that the observed frequency is greater than the expected frequency. This is useful to examine which element has a significant difference between the observed and expected frequencies - an absolute value greater than 1.96 can be considered significant for the 0.05 level.

Results pending...