Flashcards in Interpreting the evidence 1 Deck (9)

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1

## how do you calculate NNT

### 1/ ARD

2

## how do you calculate Absolute risk reduction

### risk(group1)- risk (group2)

3

## how do you calculate relative risk ratio

### risk (group1)/ risk (group2)

4

## what are odds ratios used for

### case control studies or observational studies and regression models

5

## how do you calculate odds ratios

###
number of smokers/ number of non smokers = odds of being a smoker

odds ratio = odds smoker if case/ odds smoker if control

=odds of being a smoker if you died by 60 are 6 times the odds of being a smoker in the group who lived

6

## how do you calculate standard deviation

###
sum of squared deviations from the mean / n-1

square root the answer

7

## what is standard error of the mean

###
the variability of means from different samples

a large SE indicates that there is much variability in sample means

SE is always smaller than SD because there is less variability between sample means than individual values

can also calculate the standard error of odds ratio

larger samples lead to a smaller SE

8

## how do you calculate SE

### SE= SD / sq root of n

9