Biostatistics

Question 1

Number of “new” cases/number of people at risk of acquiring that disease

Answer 1

Incidence

Question 2

Total number of cases (new + old)/whole population

Answer 2

Prevalence

Question 3

What is the importance of incidence?

Answer 3

Acute cases, e.g., incidence of Zika virus infection in August

Question 4

Attack rate

Answer 4

is the number of people with disease over the number of people at risk for the disease.

Question 4

What is the significance of prevalence?

Answer 4

Chronic cases only,a e.g., prevalence of diabetes in United States

Question 5

Identifies all patients with the disease, and if negative, can virtually rule out the diagnosis.

Answer 5

Sensitivity

Question 6

When you lower the cut off point you are ______ more patient with the disease? Another way of describing this is if a cutof of DM hba1c went from 6.5 to 5.5 how would that affect the amount of people with disease?

Answer 6

including

Question 7

When you increase the cut off you are ______ more patient

Answer 7

excluding

Question 8

Sensitivity and (PPV or NPV) go with one another?

Answer 8

NPV, and this is because as we lower the cut off this increases the amount true positives lowering the FN (increasing the NPV) and vice versa if we increase the cut off the TP go down and FN increases (decreasing the NPV)

Question 9

Specificity and (PPV or NPV) go together?

Answer 9

Specificity goes with PPV, as the cut off increases the TN go up and the false positives go down (PPV increases) and vice versa if the cut off were to decrease

Question 10

This is a rare disease reporting with details of the presentation of disease, images, treatment, and follow-up.

Answer 10

Case report

Question 11

This study is Snapshot of present time uses surveys to identify current health problems.

Answer 11

Cross sectional

Question 12

Study that starts with a risk factor and observes for disease development. The group is divided into exposed and unexposed.

Answer 12

cohort

Question 13

Starts with disease and identifies risk factors. Group is composed of patients with and without disease and mutual risk factors

Answer 13

Case control

Question 14

What is the weakness of a cohort?

Answer 14

Attrition (loss of study participants) or migration, selection bias is built in, confounding bias

Question 15

What is the weakness of a case control study?

Answer 15

Recall bias, confounding bias

Question 16

Is the graph positively or negatively skewed?

Answer 16

Positive skewed the mean will be the greatest value the median is ALWAYS the middle and the mode will be the smallest value

Question 17

Would the mean or the mode have the higher value?

Answer 17

The mode

Question 18

A pneumonic that will always help you find the mode.

Answer 18

Fat mode- Mode is the nearest to the fat portion of the graph.

Question 19

_____ % of the population lies in one standard deviation.

Answer 19

68

Question 20

______ % of the population lies within two standard deviations.

Answer 20

95

Question 21

_____ % of the population lies within three standard deviations?

Answer 21

99.7

Question 22

This statistical test has two numerical variables and example of this test (ie comparing height with income).

Answer 22

Pearson correlation

Question 23

The statistical test that has 3 or more categorical variables with a comparison of a mean value (ie the mean hba1c black, hispanic, and Indigenous and the

Answer 23

ANOVA

Question 24

The statistical test that with two categories and a dependent variable. (ie mean height between males and females)

Answer 24

T-test or Z-test

Question 25

A statistical test with two categorical variables.

Answer 25

Chi square

Question 26

The number needed to treat?

Answer 26

1/ARR Is the number of persons that need to be treated to prevent an adverse event.

Question 27

The number needed to harm?

Answer 27

1/ARI, how many treatments before an adverse event.

Question 28

What is the p value?

Answer 28

The probability that the null hypothesis is true. ie if a person has a p value of <0.05 that indicates that there is a less than 5% chance that the null hypothesis would be true.

Question 29

What is a type 1 error

Answer 29

You said there is a relationship when in reality there isn't (false positive)

Question 30

What is a type 2 error

Answer 30

You said there is no relationship when there is a relationship

Question 31

Relative risk

Answer 31

the risk of disease in exposed group/ the risk of disease in the unexposed group

Question 32

Odd ratio

Answer 32

AD/ BC or (A/B)/(C/D)

Question 33

absolute risk reduction

Answer 33

CER (c/c+d) - EER (a/a+b)

Question 34

Attributable risk

Answer 34

EER (a/a+b) - CER (c/c+d)

Question 35

This bias prolongs the survivor rate because disease detection is determined earlier?

Answer 35

Lead time bias

Question 36

Confounding variables

Answer 36

Both the independent variable and other external factors can influence the dependent variable (outcome)

Question 37

What prevents cofounding varibales?

Answer 37

Matching

Question 38

What is case fatality?

Answer 38

The number of persons with the disease over the number of people that die from the disease.