# Biostats/Epi Week 6 Flashcards

1
Q

Validity

A

Ability of a test to distinguish between who has a disease & who does not

2
Q

Sensitivity

A

Ability of a test to correctly identify those who DO HAVE a disease

3
Q

Specificity

A

Ability of a test to correctly identify those who DO NOT HAVE a disease

4
Q

Dichotomous results

A

Yes or no

Does have or does not have

5
Q

False Positive

A

Screened positive but does not actually have the disease

6
Q

False Negative

A

Screened negative but actually does have the disease

7
Q

Problems of false positive

A

\$ Brought back for further testing: expensive, possibly invasive
\$ Patient anxiety
\$ Labeling despite subsequent evaluation as negative

8
Q

Problems of false negative

A

\$ Serious diseases are not caught & treated as early as possible

9
Q

Continuous variable testing

A

Test for which there is no positive or negative & a cutoff point must be marked

10
Q

Sequential (two-stage) testing

A

Less expensive/invasive/uncomfortable test first, then more expensive/invasive/uncomfortable for patients who test postive on first test

11
Q

Net sensitivity

A

Number of people with disease who tested positive over multiple tests/total number of people in tested group who have disease

12
Q

Net specificity

A

Number of people without disease who tested negative/total number of people in tested group who did not have disease

13
Q

Simultaneous testing

A

Using two different tests at the same time

14
Q

Percent agreement

A

Add the numbers in all cells which have agreement by both observers/divide that sum by total number of results read, then multiply by 100 to get percentage

15
Q

Predictive value

A

Number of true positives/total number who tested positive (true+false positives)

16
Q

Negative predictive value

A

Number of true negatives/all those who tested negative (true+false negatives)

17
Q

What type of analysis is this: comparison at the end of a study investigating the effectiveness of treatment for multiple myeloma by examining the survival rates for one-half of the population.

A

Median survival time

18
Q

What type of analysis is this: Comparison of survival each year within two large randomized control clinical studies investigating African American males with Hypertension. One group receives an ACEI and one group receives a Ca Channel Blocker. Loss to treatment occurred each year of the 5 year study.

A

Standard life table

19
Q

What type of analysis is this: Comparison of survival rate for children, ages 8-12, who have experienced closed head trauma.

A

Relative survival rate

20
Q

What type of analysis is this: Comparison of a small group of women, ages 45-55, receiving a new treatment for endometrial cancer. The researcher wants to know the cumulative proportion surviving to the end of the study.

A

Kaplan Meier life table

21
Q

Primary care is an intervention that occurs in community based health centers and is primarily considered primary, secondary, or tertiary prevention?

A

Secondary

22
Q

The decision whether or not to screen a population for a disease should be based on:

A

Whether the case-fatality rates will decrease

23
Q

In order to quantify survival time, the duration of survival is counted from the time of:

A

Diagnosis

24
Q

How does case-fatality rate differ from mortality rate?

A

denominator is the number of individuals who have the disease

25
Q

Health care providers create a clinical diagnosis, but order tests to confirm the suspected disease. To predict the value of the test when the disease is infrequent, the two factors to consider are

A

prevalence and specificity (Gordis Ch 5)

26
Q

In a test evaluating a new dieting program, participants who were lost to follow up were not included in the statistical results. What type of bias is this?

A

Referral bias

27
Q

Decreased all-cause mortaliy rates in a non-randomized trial evaluating the effect of Treatment B in adult white females in suburban America. What type of bias does this show?

A

Prognostic selection

28
Q

In reviewing the raw statistics, the screening for Disease A increased survival time. No additional years of survival was attained. What type of bias does this show?

A

29
Q

Reduction in occurrances of stroke through early identification of TIAs with use of a CT scan with contrast of brain. What type of bias does this show?

A

Over-diagnosis

30
Q

NAATs (DNA tests) may not be useful for conducting studies of susceptibility to Chlamydia trachoma re-infection or test-of-cure because a positive NAAT result could reflect a variety of states and conditions, including remnants of DNA from a previous infection. This knowledge will result in a change in practice because the ­­­­­­­­­­­­­­­­­­­­­___________ of NAATs in test-of-cure cases is uncertain.

A

validity. Gordis, Chapter 5, p. 86. Validity is a test is defined as the ability to distinguish between those who have a disease and those who do not. In this case, the re-test may detect remaining DNA, identifying the person who is treated and not now infected, but still carries the DNA for the dead Chlamydia trachoma. Therefore, the CT test-of-cure must be a culture! (because the re-test NAAT is not valid).