Midterm 2

Question 1

Classic definition of probability

Answer 1

if an event can occur in N equally likely ways, and i m of these possess characteristic E, then probability of E, P(E), is m/N

Question 2

Relative frequency definition of probability

Answer 2

the probability of an event denotes the relative frequency of occurrence of that event in the long run

Question 3

Sample prevelance

Answer 3

estimate of the population prevalence

Question 4

Conditional probability

Answer 4

probability of being ____ if you know you’re _____

Question 5

Independent events

Answer 5

probability of one is not affected by the occurrence or non-occurrence of the other

Question 6

Relative risk = 1

Answer 6

disease and exposure are independent

Question 7

Sensitivity

Answer 7

how good a test is at finding disease among those diseased

Question 8

Specificity

Answer 8

how good a test is at ruling out disease among those not diseased

Question 9

False negative rate =

Answer 9

1 - sensitivity

Question 10

False positive rate =

Answer 10

1 - specificity

Question 11

Positive predictive value (PPV)

Answer 11

probability of having disease amongst those who test positive

Question 12

Negative predictive value (NPV)

Answer 12

probability of not having disease amongst those who test negative

Question 13

ROC curve

Answer 13

plots all possible cutoffs in terms of sensitivity and specificity

Question 14

AUC (area under ROC curve)

Answer 14

gives measure of how good the continuous variable is at predicting the outcome

Question 15

Continuous data

Answer 15

data that can take on an infinite number of values between any two points

Question 16

Probability density functions

Answer 16

describe the distribution in the entire population

Question 17

Is density positive or negative?

Answer 17

positive