Biostatistics

Question 1

Continuous data

Answer 1

data with numeric values

-age, weight, height, A1c, etc

Question 2

Categorical data

Answer 2

data with categorical values

-gender, race, exposure/disease status

Question 3

Normal Distribution

Answer 3

symmetrical around the mean, bell shaped

Question 4

normal distribution: -1σ to +1σ

Answer 4

68%

Question 5

normal distribution: -2σ to +2σ

Answer 5

95%

Question 6

normal distribution: -3σ to +3σ

Answer 6

99.7%

Question 7

Bimodal distribution

Answer 7

suggestive of two different population

Question 8

right skewed distribution

Answer 8

mode

Question 9

left skewed distribution

Answer 9

mean>median>mode

Question 10

Descriptive statistics for continuous data

Answer 10

measures of central tendency: mean, median, mode

measures of dispersion: variance, SD

graphic representation: histogram, box plot, line graph

Question 11

Descriptive statistics for categorical data

Answer 11

frequency

proportion: rate, ration, prevalence, incidence rate, relative risk, odds ratio, sensitivity, specificity
graphic: pie chart, bar graph

Question 12

Measures of central tendency

Answer 12

Mean: sum of values/total # of values

Median: value in middle of a ranked data

Mode: value that occurs most often

Question 13

Measures of dispersion

Answer 13

Variance: (sum of square of deviance from mean) divided by (total number of variable - 1)

SD: square root of variance

Standard error of mean: SD / (square root of total number of values)

Question 14

Inferential statistics

Answer 14

to make an inference for a population group from a sample group

Question 15

Population group

Answer 15

complete collection to be studied

Question 16

Sample group

Answer 16

Part of the population of interest selected for study

Question 17

Goal of Statistical Hypothesis Testing (SHT)

Answer 17

make decisions about a population from a sample

Question 18

Procedure of SHT

Answer 18

1. state null hypothesis
2. state alternative hypothesis
   3 select level of significance
3. collect and summarize the sample data into a statistic
4. refer to a criterion for evaluating the sample evidence producing p-value
5. make a decision to reject/retrain null hypothesis based on p-value

Question 19

Significance level

Answer 19

standard defined by probability of rejecting a true null hypothesis (false positive)

Question 20

P value

Answer 20

quantifies how consistent your sample statistics are with the null hypothesis

Question 21

high p value

Answer 21

same results are consistent with null hypothesis that is true

Question 22

low p value

Answer 22

your sample results are not consistent with a null hypothesis which is true

Question 23

Type I error

Answer 23

false positive

Question 24

Type II error

Answer 24

false negative

Question 25

Power

Answer 25

true positive

Question 26

confidence interval

Answer 26

quantifies the uncertainty in the estimates

the narrower interval implies higher precision with less variability

the wider interval implies lower precision with increased coverage

Question 27

If CI contains a null value

Answer 27

it fails to reject null hypothesis

Question 28

If CI does not contain null value

Answer 28

it rejects the null hypothesis

Question 29

Student’s t-test

Answer 29

compares means of 2 independent groups

Question 30

ANOVA

Answer 30

compare means of 3 or more independent groups

Question 31

Chi-square test

Answer 31

compare the proportions/ratios between independent groups