Dear R users,
I think i have a simple question which i want to explain by an example; i have several 2-digit industry codes that i want to use for conducting by-industry analysis but i think there is a problem with the degrees of freedom! for example, when i do my analysis without any 2-digit industry code, i got the following summary (i have 146574 observations in total): > abc<-lm(lnQ~lnC+lnM+lnL+lnE+eco+inno, data=ds) > summary(abc) Call: lm(formula = lnQ ~ lnC + lnM + lnL + lnE + eco + inno, data = ds) Residuals: Min 1Q Median 3Q Max -11.01340 -0.17637 -0.02217 0.14974 7.79005 Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 0.8870369 0.0050646 175.144 <2e-16 *** lnC 0.0658922 0.0006549 100.614 <2e-16 *** lnM 0.8027478 0.0006549 1225.764 <2e-16 *** lnL 0.0173622 0.0004025 43.138 <2e-16 *** lnE 0.0657710 0.0006745 97.516 <2e-16 *** ecoTRUE 0.0101649 0.0045892 2.215 0.0268 * innoTRUE 0.0945100 0.0030317 31.174 <2e-16 *** --- Signif. codes: 0 *** 0.001 ** 0.01 * 0.05 . 0.1 1 Residual standard error: 0.294 on 146160 degrees of freedom (407 observations deleted due to missingness) Multiple R-squared: 0.9705, Adjusted R-squared: 0.9705 F-statistic: 8.027e+05 on 6 and 146160 DF, p-value: < 2.2e-16 as we can see from the last row there are 146160 DF (407 deleted) this is ok! but when i want to use for example just one of the industry lets say just the 11th industry 1st: i create the dummy for this industry such as; >ind1=(ind_2d==11)# so here the R supposed to consider just the 11th industry!! > abc<-lm(lnQ~lnC+lnM+lnL+lnE+eco+inno+ind, data=ds) > summary(abc) Call: lm(formula = lnQ ~ lnC + lnM + lnL + lnE + eco + inno + ind, data = ds) Residuals: Min 1Q Median 3Q Max -11.03392 -0.17647 -0.02301 0.14901 7.74957 Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 0.8980397 0.0050451 178.001 < 2e-16 *** lnC 0.0672255 0.0006523 103.065 < 2e-16 *** lnM 0.7990819 0.0006579 1214.596 < 2e-16 *** lnL 0.0171633 0.0004004 42.870 < 2e-16 *** lnE 0.0670030 0.0006716 99.770 < 2e-16 *** ecoTRUE 0.0162249 0.0045672 3.552 0.000382 *** innoTRUE 0.0966967 0.0030160 32.062 < 2e-16 *** indTRUE -0.1251466 0.0031509 -39.717 < 2e-16 *** --- Signif. codes: 0 *** 0.001 ** 0.01 * 0.05 . 0.1 1 Residual standard error: 0.2924 on 146159 degrees of freedom (407 observations deleted due to missingness) Multiple R-squared: 0.9709, Adjusted R-squared: 0.9709 F-statistic: 6.957e+05 on 7 and 146159 DF, p-value: < 2.2e-16 but as we can see it again counted in all the industries! so the DF is 146159!!! So i just wonder, where do i made mistake, or there is no mistake at all, and i just misunderstood the DF issue? Any answer would be appreciated thanks in advance _________________________________________________________________ [[alternative HTML version deleted]]
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