Statistical terms

Question 1

The average of a series of observed values

Answer 1

Mean

Question 2

The middle value if series of observed values are placed in order

Answer 2

Median

Question 3

The value that occurs most frequently within a dataset

Answer 3

Mode

Question 4

The difference between the largest and smallest observed value

Answer 4

Range

Question 5

Levels of evidence

Answer 5

Ia - evidence from meta-analysis of randomised controlled trials
Ib - evidence from at least one randomised controlled trial
IIa - evidence from at least one well designed controlled trial which is not randomised
IIb - evidence from at least one well designed experimental trial
III - evidence from case, correlation and comparative studies
IV - evidence from a panel of experts

Question 6

Grading of recommendation

Answer 6

Grade A - based on evidence from at least one randomised controlled trial (i.e. Ia or Ib)

Grade B - based on evidence from non-randomised controlled trials (i.e. IIa, IIb or III)

Grade C - based on evidence from a panel of experts (i.e. IV)