Biostatistics

Question 1

Confounding

Answer 1

a 3rd variable that hasn’t been considered but muddies the exposure & outcome bc is is related to both
i.e. (EtOH & bladder cancer seem associated until you realized smoking & bladder cancer are assoc. and smokers are more likely to drink)

Question 2

Lead-time Bias

Answer 2

Artificial increase in pt survival time who actually have an unchanged prognosis, when in reality they were just diagnosed earlier

Question 3

T-test

Answer 3

compares the mean of 2 groups of subjects

Question 4

Chi-square test

Answer 4

compares the mean of >/= 3 groups; categorical data

Question 5

Correlation Coefficient

Answer 5

0= no correlation, 1= perfect correlation, -1= perfectly inverse correlation

Question 6

Positively Skewed Distribution

Answer 6

Mean > Median > Mode

Question 7

Negatively Skewed Distribution

Answer 7

Mean

Question 8

Hawthorne Effect

Answer 8

subjects change behavior when they find out they are being studied

Question 9

Pygmalian Effect

Answer 9

Bias based on investigator bias and the inability to see the results in an unbiased manner