knockout: 6 mice, 1864 spines on 1370 um; mouse densities 11.2 to 15.9 per 10 um
wild-type: 6 mice, 1589 spines on 1397 um; mouse densities 9.2 to 14.5 per 10 um
A. Segments as n (72 vs 72), Welch t-test: knockout / wild-type 1.22, p = 0.00027
B. Neurons as n (36 vs 36), Welch t-test: knockout / wild-type 1.21, p = 0.0033
C. Mice as n (6 vs 6), Welch t-test on spines per 10 um: difference 2.32 (95% CI -0.31 to 4.94), p = 0.078
D. Poisson model of all segments, log(length) offset, mice ignored: rate ratio 1.20, likelihood-ratio chi2(1) = 27.55, p = 1.5e-07