In reaction to my refutation of their contention that Catholic school pupils have higher achievement than public school pupils (Noell, 1982), Coleman, Hoffer and Kilgore (1982, hereafter referred to as CHK) raise a redherring. They assert that my analysis is flawed by misspecification, . . in particular, the misspecification by failure to allow for different regression lines in the public and private sector (CHK, 1982: 168). I pooled together Catholic and public school pupils for my analysis; CHK separated them, running separate regressions for each group. If only, CHK assert (CHK, 1982: 166), I had done a Chow test for equality of error variance of the two groups, I would never have combined them. But this is not so. The Chow procedure, which is really a kind of analysis of variance (see Johnston, 1972), tests for equality between coefficients in two linear regressions. This is equivalent in our case to testing for significant interactions between school type (public-Catholic) and the other background variables. Table 1 presents the R2s for our ENHANCED senior and sophomore regression equations with and without interaction terms, using reading and mathematics achievement scores as the dependent variables (see Noell, 1982 for details). As is readily apparent, the increment in R2 due to inclusion of the interaction terms, which allows different regression lines in the public and Catholic school sectors, is trivial and not substantively meaningful. In all cases it is less than one-half percent. Although this increment is statistically significant in most cases because of the large sample size, it is hardly the basis for meaningful analysis of the differential effects of public and Catholic schools (also see Kerlinger and Pedhazur, 1973:259, who discuss this type of situation and advocate the strategy I pursued). My refutation of CHK stands.