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