Statistics

Question 1

Type 1 error?

Answer 1

False positive / reject null hypothesis when it’s true

Question 2

Power is usually set at?

Answer 2

80%

Question 3

Type 2 error?

Answer 3

False negative / accept null hypothesis when there is a real difference

Question 4

How to calculate standard deviation?

Answer 4

square root of variance

Question 5

How to calculate standard error?

Answer 5

standard deviation / Square root (n sample size)

Question 6

How to calculate positive likelihood ratio?

Answer 6

(Sensitivity) / (1 - Specificity)

Question 7

How to calculate negative likelihood ratio?

Answer 7

(1 - Sensitivity) / (Specificity)

Question 8

Correlation coefficient of +1 indicates

Answer 8

perfect positive relationship

Question 9

Correlation coefficient of -1 indicates

Answer 9

perfect negative relationship

Question 10

Proportion of group contained inside 1 standard deviation?

Answer 10

68%

Question 11

Proportion of group contained inside 2 standard deviations?

Answer 11

95%

Question 12

Case control study used for?

Answer 12

RARE disease
Finds cases and retrospectively looks at risk factors

Question 13

Cohort study?

Answer 13

Cause and effect in chronological order
Prospective

Question 14

Interquartile range is?

Answer 14

25th-75th centiles
therefore contains half of the data

Question 15

Central line on box whisker plot is…

Answer 15

Median

Question 16

Points at end of the whiskers are…

Answer 16

2.5 and 97.5 values

Question 17

What does the confidence interval tell you?

Answer 17

Degree of uncertainty