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Flashcards in Statistics Deck (21)
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1
Q

Paired t-test

A

Use with paired samples or individuals (matched pts or BPs before and after drug)
**Compares two samples in the same patient or in matched patients

2
Q

Unpaired t-test

A

Compares means of two independent samples/groups

3
Q

ANOVA

A

Analysis of Variance

**Different between the means of 3 or more groups

4
Q

Chi-square

A

Difference between 2 or more percentages or proportions of categorical outcomes (NOT MEANS)

5
Q

Relative Risk

A

Risk of disease in exposed/risk of disease in unexposed

**Cohort studies

(A/A+B)/(C/C+D)

6
Q

Odds ratio

A

Case-control; approximates relative risk in a rare disease

AD/BC

7
Q

Null hypothesis

A

No difference; no associated between disease and risk factor

8
Q

Alternative hypothesis

A

There is a difference; risk factor is associated with disease

9
Q

Type I/alpha error

A

Rejecting the null hypothesis when it is tru

Usually set alpha to 0.05

10
Q

Type II/beta error

A

Accepting the null hypothesis when it is false

11
Q

Power

A

Probability of rejecting the null hypothesis when it is false (saying there is a difference when there really is)

Depends on # of endpoints and differences in means

Power=1-beta

12
Q

Ordinal vs nominal variables

A

Nominal = names (sex, marital status)

Ordinal = ordered (stage, pain)

13
Q

Sensitivity

A

Chance of a positive test in a patient with disease

of true positives/# of all people with disease

A/A+C

14
Q

Specificity

A

Chance of a negative test in a negative patient

D/B+D

1- specificity = false positive rate

15
Q

Positive predictive value

A

Probability of having a condition with a positive test

of true positives divided by # who tested positive for disease

A/A+B

16
Q

Negative predictive value

A

Probability of not having a condition with a negative test

of true negatives divided by # of people who tested negative for the disease

D/C+D

17
Q

Mann-Whitney (Wilcox rank test)

A

Non-parametric analog to t-test

18
Q

Kruskal Wallis

A

Compares the means of two populations that are NOT normally distributed

19
Q

Kaplan Meier

A

Compares survival rates among groups

20
Q

Cox regression (Cox proportional hazards model)

A

Mutlivariate survival analysis - evaluates association between variable and survival; controls for confounding variable

21
Q

What is kappa?

A

Measure of reproducibility - > 0.75 = excellent; <0.4 = poor