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Flashcards in Probability and Statistics Deck (37)
1

2 ways a study can screw the pooch

caused by chance (random error)

not caused by chance (bias or systematic error)

2

what deals with random errors

statistical inference

3

T/F random errors bias a study

false

may be wrong but not biased

4

what is a systematic error

error that is inherent to the study method being used and results in a predictable and repeatable error for each observation

5

T/F systemic errors bias a study

true

6

T/F there is a formal method to deal with systematic errors

false

7

tests of statistical inference

estimate the likelihood that a study result was caused by chance

8

T/F statistically significant means clinically important or meaningful

false

9

what is a chance occurrence

something that happen unpredictably without discernible human intention or with no observable cause

10

random variation

there is error in every measurement

if measure something over an over again will get slight variations in measurements

11

what does statistical inference tell us

if we measure something only once, how sure are we that our measurement has been caused by chance

12

what 2 methods are used to estimate random variation in a study

confidence intervals
p-values

13

T/F width of the CI is related to sample

true
- small samples have large CI
- large samples have small CI

14

T/F if the 95% CI for the OR does not include one the OR is statistically significant

true

15

T/F the same rules apply for OR, PR, RR when it comes to CI

true

if CI spans one they are statistically insignificant and there is no association

16

what do P-values estimate

whether a measured association was likely to have been caused by chance

17

Does P-value give you information on size of sample and range of true value

it sure as shit doesn't

18

to be statistically significant p-value must be less than

0.05

19

how do you calculate p-value

chi-squared test

student's T-test

correlation

20

null hypothesis

hypothesis of no association

21

alternative hypothesis

the research question

there is an association between exposure and disease

22

T/F we use p-values or CIs accept or reject the null hypothesis

true

23

wha is a type 1 error

false positive
- reject the null when it is not false
- saying there is an association when there isn't

24

what is a type II error

false negative
- not rejecting the null when it is false
- saying there is no association when there is

25

types of data

categorical

continuous

26

categorical data

broken into discrete categories
- nominal
- ordinal

27

continuous data

variable is numeric and can have any one of many possible values

28

nominal

named, not ordered
horse vs. donkey; stallion vs. gelding vs mare vs colt vs filly

29

ordinal

named ad ordered by nor constant value between ranks
neonate vs juvenile vs adult vs geriatric

30

describe categorical data

frequency distribution

may be represented as a table or bar chart

statistical test

31

describe continuous data

frequency distribution and histogram

describe the center of the distribution

describes the amount of dispersion

describe the shape of distribution

statistical tests

32

what is central tendency

describes the center of the distribution
mean, median, mode

33

what is dispersion (spread)

describes how closely the values are gathered around the center of distribution
range, standard deviation

34

Chi-squared test

test of independence between 2 categorical variables

p-value

used for categorical data

35

student's T-test

difference in means
compare averages of 2 groups
used for continuous data

H0=means of 2 groups are the same

Ha= can be one or two tailed

36

correlation

measures the strength and direction of a linear relationship between 2 continuous variables

37

correlation coefficient (r)

often used for dose response relationships

both variables are numerical, usually continuous
- strong: r>0.80
- weak: r