The tetrachoric correlation coefficient assumes that the variable underlying each dichotomous measure is normally distributed.
2.
The tetrachoric correlation coefficient provides " a convenient measure of [ the Pearson product-moment ] correlation when graduated measurements have been reduced to two categories . " The tetrachoric correlation should not be confused with the Pearson product-moment correlation coefficient computed by assigning, say, values 0 and 1 to represent the two levels of each variable ( which is mathematically equivalent to the phi coefficient ).
परिभाषा
a correlation coefficient computed for two normally distributed variables that are both expressed as a dichotomy पर्याय: tetrachoric correlation,