Table 6. Differences of marginal means of discrimination indices across item-writing flaws.

IWF	Discrimination index (Flawed)	Discrimination index (Unflawed)	Difference in discrimination indices	Standard Error	Lower 95% confidence level	Upper 95% confidence level	P value
1	0.2178	0.2468	-0.02898	0.05189	-0.1307	0.07273	0.5765
2	0.2942	0.2474	0.04684	0.05189	-0.05487	0.1485	0.3667
3	0.2513	0.1739	0.07738	0.05189	-0.02433	0.1791	0.1359
4	0.1110	0.1434	-0.03242	0.05189	-0.1341	0.06929	0.5321
5	0.1884	0.2623	-0.07388	0.05802	-0.1876	0.03983	0.2029
6	0.2179	0.2094	0.008459	0.05189	-0.09325	0.1102	0.8705
7	0.1523	0.1668	-0.01451	0.05189	-0.1162	0.08720	0.7798
8	0.2160	0.2042	0.01180	0.05189	-0.08991	0.1135	0.8201
9	0.2981	0.2793	0.01877	0.05189	-0.08294	0.1205	0.7176
10	0.1377	0.1900	-0.05230	0.05189	-0.1540	0.04940	0.3135