11.6 Solutions: Check Your Understanding

One-sample t test: A one-sample t test found that coma survivors (M = 95.0, SD = 14.1) had verbal IQ scores that were significantly lower than 100, t(330) = -6.52, p < .001, 95% CI for true mean [-Inf, 96.2].

Independent samples t test: An independent samples t test found that the original wells of families who switched wells (M = 1.83, SD = 1.18) had significantly higher levels of arsenic compared to the wells of families who did not switch wells (M = 1.42, SD = 0.95), t(2993) = -10.60, p < .001, d = -0.39.

Paired samples t test: A paired samples t test found that there was not a significant difference between self-reported and measured weights (M_diff = -0.60, SD_diff = 8.45), t(182) = 0.96, p = .34, d_z = 0.07.

Correlation: There was not a significant correlation between nonwhite population and city density, r(98) = .002, 95% CI [-.19, .20], p = .98.