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Flashcards in EDS Deck (130)
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1

what is nominal data

categorical data which cant be ordered e.g. gender, blood group

2

what is ordinal data

categorical data which can be ordered

3

what is discrete data

numerical data which only contains whole numbers

4

what is continuous data

numerical data which has no limitations on the value e.g. height or weight

5

what is prevalence

the number of people with that condition at that point in time

6

what is incidence

the rate of new events in a time period

7

how do you calculate variance

sum of squares of residuals/degrees of freedom

8

how do you calculate degrees of freedom

sample size - number of constraints

9

how do you calculate standard deviation

square root of variance

10

what is internal validity

refers to whether the effects observed in a study are due to manipulation of the independent variable and not another factor

11

what is external validity

looks at whether the results can be generalised across the whole population

12

how do you calculate the standard deviate (z score)

x-mean/SD

13

between what range of standard deviations from the mean do 68% of the population lie

-1 and +1

14

between what range of standard deviations from the mean do 95% of the population lie

+/- 1.96

15

between what range of standard deviations from the mean do 99.9% of the population lie

+/- 3.29

16

what is pseudoreplication

where multiple measurements are taken from one individual

17

what is the standard error of the mean

the measure of the variability of the distribution of means

18

how do you calculate SEM

SD/square root n

19

how does sample size affect SEM

greater sample size gives a smaller SEM

20

how do you calculate 95% confidence internals

CI = mean +/- (1.96 x SEM)

21

what is a one tailed hypothesis

where there is a specified direction

22

what is a two tailed hypothesis

where there is no specified direction

23

what is a type 1 error

a false postiive

24

what is the error rate for type 1 errors

5%

25

how does p value affect the type 1 error rate

high p value increases type 1 error rate

26

what causes type 1 errors

publication bias, lower power, poor understanding of statistics, p-hacking

27

what are type 2 errors

false negatives (not rejecting the null hypothesis even though its false) - incorrectly concluding that there's no effect

28

what is the rate of type 2 errors

1-power

29

what is power

this is the probability of rejecting the null hypothesis when its false

30

what factors increase power

large sample size, decreased variability, larger p value