Statistics: definitions

Question 1

Null hypothesis (H0)

Answer 1

No difference between the two groups (default hypothesis)

Question 2

Alpha (type I) error

Answer 2

Incorrect rejection of the null hypothesis - conclude there is a difference when there is no true difference

Question 3

Beta (type II) error

Answer 3

Incorrect acceptance of the null hypothesis - conclude there is no difference when there is

Question 4

Standard deviation

Answer 4

Measure of the variability of the data from the mean, equal to the square root of the variance

Question 5

Standard error

Answer 5

Measures the variability of means when many similar samples were taken from the population of possible measurements - how close the sample mean is likely to be to the true population mean

Question 6

Power

Answer 6

The ability to detect a significant result where a true difference exists (the probability of rejecting the null hypothesis when the alternative hypothesis is true)

Question 7

Accuracy

Answer 7

How close a value is to the true value

Question 8

Precision

Answer 8

How consistent results are when measurements are repeated

Question 9

Validity

Answer 9

Suitability of the experimental method to address the aim of the experiment

Question 10

Internal validity

Answer 10

If outcome is related to aim

Question 11

External validity

Answer 11

If results are applicable to the wider population

Question 12

Odds ratio

Answer 12

How much more likely one group is to be in an outcome group than another