Descriptive Statistics

Question 1

simple random sample

Answer 1

every person in the population has an equal chance of being selected

Question 2

stratified random sample

Answer 2

population is separated into similar strata and then random samples are drawn from each group

Question 3

cluster sample

Answer 3

“cluster” is selected at random and then a sample is chosen from the cluster

Question 4

systematic sample

Answer 4

selecting subjects in a systematic way

Question 5

example of a cluster sample

Answer 5

randomly choosing 5 schools then choosing random students from each school

Question 6

example of systematic sample

Answer 6

every 3rd baby born, etc

Question 7

systematic samples may be prone to ___

Answer 7

selection bias

Question 8

probability: definition, range

Answer 8

chance that a particular event will occur

ranges from 0-1

Question 9

addition rule, assumption

Answer 9

the probability of Y or X = probability of X + probability of Y
assumes X and Y are mutually exclusive

Question 10

multiplication rule, assumption

Answer 10

the probability of X and Y = probability of X x probability of Y, assumes the two variables do not influence each other

Question 11

Nominal variables

Answer 11

categories

race, gender, color

Question 12

Ordinal variables

Answer 12

placed in meaningful order, but no consistent interval between
grades of cancer, pain scores

Question 13

Interval variables

Answer 13

placed in meaningful order with intervals in between but no absolute zero
degrees C

Question 14

ratio variables

Answer 14

placed in meaningful order with intervals in between and absolute zero

Question 15

relative frequency distribution shows:

Answer 15

percentage

Question 16

percentile definition

Answer 16

gives the percentage of observations that fall below the particular value (gives information about one score in relation to all of the other scores)

Question 17

mean

Answer 17

average

Question 18

mean is very sensitive to:

Answer 18

extreme scores

Question 19

median

Answer 19

divides data into 2 equal parts

Question 20

mode

Answer 20

the most frequently occurring value

Question 21

bimodal

Answer 21

when 2 scores occur with the same frequency

Question 22

variance equation

Answer 22

S2 = E(xi-x)2 / n-1

Question 23

standard deviation

Answer 23

square root of variance (s)

Question 24

coefficient of variation

Answer 24

standard deviation/mean

Question 25

mean, SD and AUC in normal distribution

Answer 25

mean= 0
SD = 1
AUC = 1

Question 26

skewed frequencies are named for their-

Answer 26

tail

Question 27

Z score indicates:

Answer 27

how many SD away from the mean an element is (in normal distribution)

Question 28

Z =

Answer 28

X - mean / standard deviation

Question 29

Z score is used to estimate:

Answer 29

the probability of an element being above or below a particular score

Question 30

% in 1 SD, 2 SDs, 3 SDs

Answer 30

1- 68%
2- 95%
3- 99.7%