Question 9 on Quiz 3 asked for the N, Mean, and Standard Deviation of IQ by hyperbili status and overall.
Because REDCap puts all data in a single table, it automatically created blank IQ records for subjects who did not have IQ tests.
If you counted the field containing the IQ scores to get N, you would get the correct answers: N = 81 for the hyperbili group and N = 162 for the non-hyperbili group. But if you counted a field containing something else, like hyperbili status, you would get 83 and 167, because 7 included subjects did not have an IQ test, but REDCap created a blank IQ entry anyway.
The Lab 3 instructions will be clarified and everybody will get full credit for the Ns, whatever you wrote. Your group means and standard deviations will be correct, but the overall mean will be incorrect, so everybody will get full credit for the overall mean.
As we will learn next week, a normalized relational database would not automatically create blank IQ values, so this problem would not occur.