Biostats

Question 1

1 SD = % ?2 SD = % ?3 SD = % ?

Answer 1

1 SD = 68% 2 SD = 95% 3 SD = 99.7%

Question 2

Bilateral Renal Agenesis associated with what condition? What other features?

Answer 2

Potter Syndrome: - b/l renal agenesis -> oligohydramnios- Grandpa facies, club feet - Pulmonary hypoplasia

Question 3

Rat poison = what drug; how to reverse?

Answer 3

Warfarin Reverse with FFP

Question 4

Biostats Formulas in Uworld

Answer 4

Q1271

Question 5

Matching cases and controls by age, race, gender decreases what?

Answer 5

Confounding

Question 6

Define latency period.

Answer 6

Latency period: time elapsed from initial exposure to clinically apparent disease. Exposure to risk modifiers sometimes occurs a significant amount of time before the exposure’s effect on the disease process is evident. And sometimes, exposure may have to be continuous for it to have effect. Q1280

Question 7

Types of Statistical Error: I vs. II

Answer 7

I: Reject null hypothesis when it is truealpha: max prob of type I error researcher accepts = p = 0.05

II: Fail to reject null hypothesis when it is false beta: max prob of type II error researcher accepts

1-beta = Power

Question 8

Power =

Answer 8

1- beta = probability of finding a TRUE relationship.

Question 9

Confounding vs. Effect modification

Answer 9

When you break up the effect based on the confounder, the association disappears.

When you break up the effect based on the effect modifier, there is significant difference in risk between the groups. Q1173

Question 10

HIPAA allows physicians to share information under what circumstances?

Answer 10

1. Patient present and says its okay

2. Patient is not present and physician determines that it is in the patient’s best interest. Just general details.

Question 11

What is the case fatality rate?

Answer 11

Number of fatal cases/ total number of people who have the disease

Question 12

What test used to compare means of 2 groups?

Answer 12

two sample t-test

Question 13

Probability at least 1 event is positive?

Answer 13

1 - Probability (all negative)

Ex: 95% negative. Draw a ball 8 times. Probability at least 1 positive = 1 - 0.95*8

Question 14

How much time does it take to reach steady state concentration when drug is eliminated by first order kinetics?

Answer 14

4-5 Half lives -.-

Question 15

What test compares the difference between the means of 2 or more groups?

Answer 15

ANOVA. Analysis of Variance.

Question 16

Formal vs. Informal addressing of patients.

Answer 16

Always formal, unless the PATIENT requests otherwise (not you asking).

Question 17

Prevalence =

Answer 17

Incidence x Time.

Question 18

Sn vs. 1-Sp curve - describe accuracy

Answer 18

Sn = TP rate; 1-Sp = FP rate

Accuracy = area under the ROC curve.

Straight line = same accuracy as random guessing. So most accurate = largest area under ROC

Question 19

Microsatellites are repeating sequences of bases that within an individual should be conserved. What germline mutations can cause accumulation of microsatellites of different lengths?

Answer 19

HNPCC - mutations in DNA mismatch repair genes that result in microsatellite instability