= Tetrachoric computation using EXCEL spreadsheet =


The program in this [[attachment:tetra.xls|spreadsheet]] will handle upto 15 dichotomous variables on upto 800 cases with missing responses assumed to be coded as blanks and the lowest valued response assumed to be coded as a '1'. The data is entered in sheet 1 and the output is a tetrachoric correlation matrix in sheet 2. Ths matrix may be copied over and entered into a SPSS spreadsheet as input to a factor analysis as described [[FAQ/polychoric| here.]]