Table 2.

Frequency of different types of responses observed in full data set (n = 356), in only those responses that addressed drift (n = 244), and before (n = 85) and after (n = 122) introductory instruction

Responses that…	% Full data set	% Addressed drift	% Before instruction	% After instruction	p Valuea
did not address drift	31.5b	NA	46.5c	23.8d	< 0.0001
contained at least one misconception	57.0	83.2	99.0	74.6	< 0.0001
hinted at knowledge of genetic drift, but were too vague to evaluate	7.0	10.2	1.0	17.0	NA
indicated some knowledge of genetic drift	7.9	11.5	1.0	11.0	0.005

^ap Values indicate significance of Fisher's exact tests comparing counts of responses before and after instruction.

^bValues in a column may sum to greater than 100%, because a response could indicate knowledge of drift and contain a misconception.

^cThe first cell in this column is calculated from all responses collected before instruction (n = 159). The rest of the cells in this column are calculated from the responses that addressed drift (n = 85).

^dThe first cell in this column is calculated from all responses collected before instruction (n = 160). The rest of the cells in this column are calculated from the responses that addressed drift (n = 122).