What were the mean DI values for CIE and control dogs, and the P-value?

• A. CIE 0.0 ± 2.0; Controls -0.5 ± 1.0; P = .50
• B. CIE 1.0 ± 3.0; Controls -1.0 ± 2.0; P = .20
• C. CIE 2.0 ± 4.0; Controls -2.0 ± 1.8; P = .08
• D. CIE 1.77 ± 4.46; Controls -2.17 ± 1.7; P = .01

Answer: (D)

Interpreting a two-group comparison requires looking at the reported means, their variability, and the P-value for the group difference. The result shows CIE dogs with a mean DI of 1.77 and a standard deviation of 4.46, while control dogs have a mean DI of −2.17 with a standard deviation of 1.7. The difference between groups is about 3.94 DI units, and the P-value of 0.01 means there is only about a 1% chance of observing such a difference if there were no real difference between the groups. This indicates a statistically significant difference in DI between CIE and control dogs, with CIE dogs having a higher mean DI on average.