Epidemiology/ Biostatistics II

Question 1

What is late look bias?

Answer 1

Information gathered at an inappropriate time (ex. Using a survey to study a fatal disease- only alive patients respond) (p.53)

Question 2

What is lead time bias?

Answer 2

Early detection confused with increased survival (p.53)

Question 3

What is observer-expectancy effect?

Answer 3

Occurs when a researcher’s belief in the efficacy of a treatment changes the outcome of that treatment (p.53)

Question 4

What is the Hawthorne Effect?

Answer 4

Occurs when the group being studied changes its behaviour owing to knowledge of being studied (p.53)

Question 5

How does sample size effect Standard Error of the Mean?

Answer 5

SEM decreases as sample size increases (p.54)

Question 6

What is type I error and how is it measured?

Answer 6

Stating that there is a difference when none exists; mistakenly accepting the alternative hypothesis and rejecting the null). Measured as alpha level, or P value; false positive error (p.54)

Question 7

What is type II error and how is it measured?

Answer 7

Stating there is not an effect or difference when one exists; failure to reject the null hypothesis when it is in fact false. Measured by beta; false negative error (p.54)

Question 8

What is power of a study and how is it measured?

Answer 8

(1-beta) is the probability of rejecting the null hypothesis when it is false or the liklihood of finding a difference if one exists. (p.55)

Question 9

Name three ways to increase the power of a study.

Answer 9

increase sample size, increase expected effect size, increase precision of measurement (p.55)

Question 10

What type of study has the highest power?

Answer 10

A meta-analysis study (p.55)

Question 11

How is a confidence interval measured?

Answer 11

CI = range from (mean-Z(SEM)) to (mean + Z(SEM)) (p.55)

Question 12

What is implied if a confidence interval for a mean difference between two variables includes zero?

Answer 12

There is no significant difference and H0 is not rejected (p.55)

Question 13

What is implied if a confidence interval for an odds ratio or relative risk includes the number one?

Answer 13

H0 is not rejected (p.55)

Question 14

What is measured by a t-test?

Answer 14

Difference between the MEANS of two groups (p.55)

Question 15

What is measured by an ANOVA test?

Answer 15

Difference between the MEANS of three or more groups (p.55)

Question 16

What is measured by a chi-squared test?

Answer 16

Difference between two or more percentages or proportions of CATEGORICAL OUTCOMES, not mean values (p.55)

Question 17

What is primary disease prevention?

Answer 17

Prevents a disease from occuring (p.55)

Question 18

What is secondary disease prevention?

Answer 18

Early detection of a disease (p.55)

Question 19

What is tertiary disease prevention?

Answer 19

Reduce disability from disease (p.55)

Question 20

Who is eligible for medicare?

Answer 20

All patients age 65 or older or patients less than 65 with certain disabilities and those with end stage renal disease (i.e. dialysis) (p.56)

Question 21

Who is eligible for medicaid?

Answer 21

People with very low incomes (p.56)