Deck 6: Biostatistics

Question 1

If we calculate an odds ratio of 1.42 and a 95% confidence interval of 0.84-2.14) then we know that the odds ratio is not statistically significant it is not significantly different from 1.0).

Answer 1

True

Question 2

In many public health studies, convenience samples are used rather than probability samples, since people who agree to participate in a study may be different from people who do not agree to participate.

Answer 2

True

Question 3

If a description of data focuses on just a single variable at a time it is called a multivariate description.

Answer 3

False

Question 4

Which of the following biostatistical terms describes a systematic difference in the results of a study from what is in fact occurring?

A) Bias
B) Dichotomize
C) Probability sample
D) Hypothetical population

Question 5

The average citizen will not be able to understand biostatistics and the methods of analysis or sources of bias in a research study, so it is best to leave all data interpretation to biostatisticians.

Question 6

Probability quantifies chance on a scale of 0 no chance) to 1 certainty).

Question 7

Randomized trials are considered the "gold standard" of research because they do not have any sources of bias whatsoever.

Question 8

Using the MACS data, we found that the adjusted odds ratio for the relationship between zidovudine treatment between visits 9 and 10 and CD4 counts <250 at visit 10 was 0.95 and the p-value was 0.88. What is the correct interpretation of this finding?

A) People who took zidovudine between visits 9 and 10 were statistically significantly more likely to have a CD4 count <250 at visit 10 compared to people who did not.
B) People who took zidovudine between visits 9 and 10 were statistically significantly less likely to have a CD4 count <250 at visit 10 compared to people who did not.
C) There was no statistically significant difference in CD4 counts <250 between people who took zidovudine between visits 9 and 10 and people who did not.
D) People with CD4 counts <250 at visit 10 were statistically significantly less likely to have taken zidovudine.

Question 9

What is a histogram?

A) A table with numerical frequencies from a research study.
B) A table used to randomly select participants for a research study.
C) A medical test to detect changes in gene expression.
D) A graphical representation of study data similar to a bar chart.

Question 10

The number of people within a certain category - such as the number of people in the 18- 44 year old age group - is a .

A) Frequency
B) Mean
C) Odds ratio
D) Variable

Question 11

A simple random sample is a type of representative sample in which all subgroups within a larger population have an equal probability of being selected.

Question 12

If a research study participant does not accurately remember his past exposures, what type of bias could be introduced?

A) Selection bias
B) Recall bias
C) Interviewer bias
D) Confounding by indication bias

Question 13

If a researcher excludes all individuals who have missing information from her analysis of study participants, she would be doing what kind of analysis?

A) A hypothetical population analysis
B) A simple random sample analysis
C) A dichotomized analysis
D) A complete-case analysis

Question 14

Why is a logistic regression model used in public health and biostatistics?

A) To calculate a five-number summary.
B) To calculate adjusted odds ratios that account for confounding variables.
C) To control for selection bias in a study.
D) To assess whether randomization

Question 15

Which of the percentiles from a five-number summary provides the median value of the distribution?

A) 0^th
B) 25^th
C) 50^th
D) 100^th

Question 16

If a treatment has a preventive effect, the odds ratio for that treatment compared to a placebo will be less than 1.0.

Question 17

A statistic calculated based on data from a random sample will be identical to a statistic calculated from any other random sample drawn from the same underlying population.

Question 18

Doing a complete-case analysis can create selection bias in a study since it eliminated data from individuals who were sampled to be study participants.

Question 19

In order to test a statistical hypothesis or determine whether a measure is statistically significant, we must calculate which measure?

A) Population odds ratio
B) Sample median
C) P-value
D) Five-number summary