Biostats 4- Cohort Studies

Question 1

This is a prospective (longitudinal) study design that compares the frequency of disease between 2 groups (exposed to risk and non-exposed) as it develops over TIME.

Answer 1

Cohort study

Question 2

This is the risk of someone developing a disease over a time-period.

Answer 2

Absolute risk

Question 3

Do you use rows or columns when determining AR?

Answer 3

rows

Question 4

This is the risk that compares the risk between 2 different groups of people.

Answer 4

Relative Risk (risk ratio)

Question 5

What is the eqn for RR?

Answer 5

RR = (AR of disease with independent factor)/(AR of disease withOUT independent factor)

Question 6

What is the significance of a RR < 1.0?

Answer 6

There is a negative association between the disease and risk.

Question 7

This is a retrospective study design that compares diseased and non-diseased groups on whether they were exposed toa hypothesized risk factor in the PAST.

Answer 7

Case-Control study

Question 8

What is the eqn for Odds Ratio (OR)?

Answer 8

OR = (odds of exposure among those WITH disease)/(odds of exposure among those withOUT disease)

Question 9

What is the significance of an OR > 1.0?

Answer 9

The disease is more likely to happen than not

Question 10

This is the probability that an event will occur divided by the probability that the event will not occur.

Answer 10

Odd

Question 11

For OR calculations, do u use columns or rows?

Answer 11

Columns

Question 12

What is the eqn for the absolute risk ratio (ARR)?

Answer 12

ARR = CER - EER

CER = Control event rate
ERR= Experimental event rate

Question 13

What is the eqn for Relative risk reduction (RRR)?

Answer 13

RRR = ARR/CER

Question 14

The inverse of the absolute risk reduction gives us what property?

Answer 14

The # needed to treat

if ARR = 20%, then 5 pts must be treated to save 1

Question 15

This quantifies the harm caused by an intervention compated with the control.

Answer 15

needed to HARM

Question 16

This is a longitudinal study design in which similar subjects are randomly allocated to 2 groups where the 2nd group is manipulated (treatment and control) and followed over time.

Answer 16

RCT

Question 17

What is the double-blind method used in RCT’s?

Answer 17

where the tester doesnt know and the pt doesnt know whether theyre getting the treatment or placebo

Question 18

What are the 2 tests u use when comparing a mean to a population?

Answer 18

CI or Z-test

Question 19

What are the 2 tests u use when comapring group means?

Answer 19

T-test or ANOVA

Question 20

What are the 2 tests u use when measuring association?

Answer 20

Correlation or Regression analysis

Question 21

This is the test type to estimate an unknown population mean from sample data.

Answer 21

Confidence intervals.

Question 22

What is the significance if the calculated value is WITHIN the 95% CI?

Answer 22

The value or result is NOT statistically significant

Question 23

This is the half-width of a CI, and is a measure of the precision of an estimate for a given level of confidence.

Answer 23

Margin of Error (MOE)

Question 24

What 2 things does a MOE reflect?

Answer 24

Mean and esimate of variability.

Question 25

True or False: if the MOE > the % difference, you cannot estimate the results.

Answer 25

True

Question 26

What is the eqn for SE?

Answer 26

SE = SD/(sample size)^-1/2

Question 27

What is the eqn for CI?

Answer 27

CI = mean +/- CL(value)*SE

Question 28

This is the tests that determins whethere a significant difference exists between a samples proportion (count) and the KNOWN population.

Answer 28

Z-test