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Flashcards in Biostats Deck (41):
1

sensitivity

TP/(TP+FN)

2

specificity

TN/ (TN+FP)

3

PPV

TP / (TP+FP)

4

NPV

TN / (TN+FN)

5

incidence vs. prevalence vs. attack rate

incidence = # new cases/ # vulnerable
prevalence = #existing cases/population at risk
attack rate = #sick/ #who were exposed

6

OR

(a/c)/(b/d) = ad/bc

7

RR

(a/(a+b)) / (c/(c+d))

8

relative risk reduction

1 - RR

9

attributable risk

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

10

Absolute risk reduction

difference in risk compared to control

11

NNT

1 / ARR

12

number needed to harm

1 / AR

13

random error

reduces the precision in a test

14

systematic error

reduces the accuracy of a test

15

examples of selection bias

- berkson bias (study only looking at inpatients), loss to follow up, health care worker study

16

measurement bias

Hawthorne effect - pts who know they are being studied behave differently than they normally would

17

positive skew data

mean > median > mode
- curve leans to the left (tail goes positive)

18

negative skew data

mean < median < mode
- curve leans to the right (tail goes negative)

19

type I error (a)

- stating that there is an effect or difference when there isn't one
- a is the probability of making a type 1 error, if p <0.05 then there is a less than 5% chance that the data will show something that is not really there

20

type II error (b)

- stating that there is not an effect or difference when one exists
- b is the probability of making a type II error
- 1-b is the statistical power, which is the probability of rejecting the null hypothesis when it is false (aka probability of finding a true relationship)
- increased power and decreased b by increasing sample size, increasing expected effect size and increasing precision of measurement

21

calculating 95% confidence interval

- 95% CI = Mean +/- 1.96*SD/sqrt n

22

t test

checks differences between the means of 2 groups

23

ANOVA

checks differences between means of 3 or more groups

24

chi-square test

checks differences between 2 or more percentages or proportions of categorical outcomes (not mean values)

25

pincer grasp

10 months

26

babinski disappears

12 months

27

points to objects

12 months

28

stranger anxiety

6 months

29

separation anxiety

9 months

30

object permanence

9 months

31

first words

10 months

32

number of cubes they can stack

age in years x 3

33

feeds self with fork/spoon

20 months

34

kicks ball

2 years

35

200 words

2 years

36

1000 words

3 years

37

line, circle or stick figure

4 years

38

hops on one foot

4 years

39

grooms self/buttons buttons

5 years

40

cooperative play

4 years

41

tells detailed stories

4 years