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Flashcards in Statistics Deck (13):
1

Variance =

Variance = SD squared

2

Standard Error =

SD / Square root (n)

3

Positive skew - highest to lowest mean median mode

Positive skew, Mean > Median > Mode

4

Negative skew

Mode > Median > Mean.

The skew pulls the mean and median in its direction.

The mode is the least changed by skew.

5

Normal distribution

Mean = Median = Mode

6

Type 1 error

rejecting a correct null hypothesis,
false positive error

7

Type 2 error

not rejecting an incorrect null hypothesis.

8

Attributable risk

AR = a/(a+b) - c/(c+d)

AR = Prevalence of disease in the exposed group - prevalence of the disease in the non-exposed

9

Absolute risk reducion

The reverse of the attributable risk.

ARR = c/(c+d) - a/(a+b)

Percentage of people who got the disease with no intervention - the percentage of people who got the disease after the treatment.

10

Number needed to treat

NNT = 1/ARR

Pirates love treats ARR!

11

Number needed to harm

NNR = 1/AR

hARm
1/AR

12

LR+, positive likelihood ratio

LR+ = sensitivity/1-specificity = true positive % / false positive %

13

LR-, neg LR ratio

= 1 - sensitivity / specificity = False negative rate / True negative rate