Biostats

Question 1

Categorical data

Answer 1

Data fits into one of several categories
Ex: gender

No order (male = female)
No magnitude (size)
No decimals used

Question 2

Integer data

Answer 2

Whole number that can be positive negative or zero
Ex: Number of blood cultures

Ordered (1<2)
Magnitude differences (size difference)
No decimals

Question 3

Ordinal data

Answer 3

Data that has natural, ordered categories
Ex: ROP stage

Ordered (1<2)
No magnitude difference
No decimals used

Question 4

Continuous data

Answer 4

Data whose value can be obtained by measuring
Ex: birth weight

Ordered
Magnitude difference
Decimals used

Question 5

Mean

Answer 5

Average
Sum of all values / N
Most sensitive to outliers

Question 6

Median

Answer 6

Middle value

Question 7

Mode

Answer 7

Most common value

Peak

Question 8

Range

Answer 8

Highest - lowest

Outliers can skew this

Question 9

Interquartile range

Answer 9

75th % - 25th %
(middle 50%)
Eliminates outliers

Question 10

Mean deviation

Answer 10

(Sum |X-mean|) / N

Hard to manipulate

Question 11

Standard deviation

Answer 11

Average distance of each value from the middle

Question 12

What kind of error do you have if you reject the null hypothesis when it is true?

Answer 12

Type 1 (alpha) error
Concluding there is a difference between groups when there is not
False positive

Question 13

What kind of error do you have when you accept the null hypothesis that is false?

Answer 13

Type 2 (beta) error
Concluding there is no difference between groups when there is
False negative

Question 14

What statistical test should you use to compare 2 separate groups of continuous data?

Answer 14

Unpaired t-test

Question 15

What statistical test should you use to compare 2 paired groups of continuous data?

Answer 15

Paired t-test

Question 16

What kind of statistical test should you use to compare three or more groups of continuous data?

Answer 16

Analysis of variance (ANOVA)

Multiple regression

Question 17

What kind of statistical test should you use to compare 2 separate groups of categorical data?

Answer 17

Chi-square test

Question 18

What kind of statistical analysis should you use to compare 2 paired groups of categorical data?

Answer 18

McNemar’s

Question 19

What kind of statistical test should you use to compare three or more groups of categorical data?

Answer 19

Chi-square

Logistic regression

Question 20

Nonparametric test for two separategroups of continuous data?

Answer 20

Man Whitney

Question 21

Nonparametric test for two paired groups of continuous data?

Answer 21

Wilcoxon

Question 22

Nonparametric test for three or more unmatched groups of continuous data?

Answer 22

Kruskal Wallis

Question 23

The P value is the same as what type of error?

Answer 23

Type 1 or alpha error

Question 24

What does the P value tell you?

Answer 24

The probability of observing a difference at least this large by chance alone

Question 25

What does the confidence interval tell you?

Answer 25

Based on the sample standard deviation and its size you are 95% confident that the limits cover the true value for the population mean

Question 26

What is a Case series?

Answer 26

Choosing cases with an exposure and following them to see the outcome

Question 27

What is a case control study?

Answer 27

Finding patients with an outcome (and control patients) and looking back to see if either group was exposed

Question 28

What is a cohort study?

Answer 28

Finding patients with or without an exposure/disease and following forward to see what their outcome is  Less biased than case control studies

Question 29

What is a Randomized controlled trial?

Answer 29

Randomly chosen cases and controls (exposed/non-exposed) followed to see their outcome

Question 30

Which type of study is not good for rare outcomes?

Answer 30

Cohort study

Question 31

What does relative risk reduction tell you?

Answer 31

The risk of an adverse outcome in the experimental group is reduced by this proportion relative to controls

Question 32

What does an odds ratio tell you?

Answer 32

Odds of adverse outcome in experimental group reduced by this proportion relative to controls

Question 33

What does absolute risk reduction tell you?

Answer 33

Risk of adverse outcome in the experimental group is reduced by this absolute percentage

Question 34

Odds ratio = relative risk when the prevalence of disease is ___

Answer 34

Low

Question 35

Odds ratio will always ____ The effect size compared to relative risk

Answer 35

Overestimate

Question 36

What does sensitivity mean?

Answer 36

How many patients with the disease will have a positive test

Question 37

What does specificity mean?

Answer 37

How many patients without the disease will have a negative test

Question 38

What does positive predictive value mean?

Answer 38

How many patients with a positive test actually have the disease Affected by disease prevalence

Question 39

What does negative predictive value mean?

Answer 39

How many patients with a negative test actually don’t have the disease Affected by disease Prevalence

Question 40

Run chart rules

Answer 40

1. Shift: >6 points above or below the median 2. Trend: >5 points upper down in a row 3. Two few or too many runs 4. Astronomical Datapoint

Question 41

What does a SMART aim need to be?

Answer 41

``` Specific Measurable Achievable Relevant Time-limited ```

Question 42

What is a process measure?

Answer 42

A measure tracking whether you were following protocols

Question 43

What is an outcome measure?

Answer 43

Whether you meet your goal

Question 44

What is a balancing measure?

Answer 44

Looking at possible trade-offs

Question 45

Standard deviations

Answer 45

1SD 68% 2SD 95% 3SD 99.8%

Question 46

Ways to increase power of a trial

Answer 46

Increase sample size Increase effect size Increasing type one error rate Decreasing standard deviation of the outcome

Question 47

Which is more important, the absolute difference or the relative difference?

Answer 47

Absolute difference