Interpreting evidence

Question 1

name some different data types

Answer 1

numerical data: continuous, discrete

categorical data: ordinal, nominal

Question 2

when is standard deviation more appropriate

Answer 2

when the data is not skewed

if skewed then use an interquartile range

Question 3

what does 25th percentile mean

Answer 3

25% of data lies below this value

Question 4

what is standard deviation

Answer 4

determines how far from the mean value each individual value is and summarizing this difference across all observations

Question 5

what does positively skewed mean

Answer 5

the data lies towards the lower end of the scale

Question 6

what is the event rate

Answer 6

the number of people experiencing an event as a proportion of the number of people in the population

Question 7

what is the relative risk reduction

Answer 7

the difference in event rates between two groups, expressed as a proportion of the event rate in the untreated group
usually constant across populations with different risks

Question 8

what is the absolute risk reduction

Answer 8

the arithmetic difference between 2 event rates

varies with the underlying risk of an event in the individual patient

becomes smaller when event rates are low (e.g. low risk patients vs high risk patients)

Question 9

what is the number needed to treat

Answer 9

the number of patients who would have to receive a treatment for one of them to benefit

calculated by 100/ absolute risk reduction (percentage)

Question 10

what is the number needed to harm

Answer 10

the number of patients who would have to receive a treatment for one of them to experience the adverse effect

calculated by 100/ absolute risk increase (percentage)
ie the inverse of the absolute risk reduction