Chi Square test of independence is used to assess whether paired observations on two variables, expressed in a contingency table, are independent of each other.
For example, given the the contigency table shown below:
A user can follow the steps below to set up a Strategy project to get the Chi Square test statistics.
1. Add the following three tables to Warehouse (number of rows or columns can be more than two)
2. Create the following schema objects
- Attribute Row: Use ID_Row as ID form, DESC_Row as DESC form
- Attribute Column: Use ID_Column as ID form, DESC_Column as DESC form
- Fact Frequency: Map to Frequency column
3. Create the following Metrics
- Frequency
- RowTotal
- ColumnTotal
- GrandTotal
- EstimatedFreq: ((RowTotal * ColumnTotal) / GrandTotal)
- SquaredDiff: (((Frequency - EstimatedFreq) * (Frequency - EstimatedFreq)) / EstimatedFreq)
- SumSquaredDiff: Sum(SquaredDiff) {~}
- Number of Rows
- Number of Columns
- DF: (( - 1) * ( - 1))
- ChiSquareTest: ChiSquareDistribution(SumSquaredDiff, DF)
4. Create a report, put SumSquaredDiff and ChiSquareTest on the grid. Result is as follows,
