H&S Calculations

Question 1

How to find true prevalence?

Answer 1

(TP+ FN)/n

Question 2

How to find apparent prevalence?

Answer 2

(TP+FP)/n

Question 3

What calculation is used in cost effectiveness?

Answer 3

Incremental cost effectiveness ratio

Question 4

What is 1 standard deviation?

Answer 4

68% of data contained

Question 5

What is 2 standard deviations?

Answer 5

contains 95% of data

Question 6

What is 3 standard deviations?

Answer 6

Contains 99.7% of data

Question 7

How to find standard error?

Answer 7

Standard deviation/ square root of sample size

Question 8

How to find standard deviation?

Answer 8

(X- mean)2 / sample size -1

X is the individual sample value and you do this for each individual sample

Question 9

What is the z score for 50% CI

Answer 9

0.65

Question 10

What is the z score for 90%?

Answer 10

1.645

Question 11

What is the z score of 95%

Answer 11

1.96 + or -

Question 12

What is the z score for 99%?

Answer 12

2.575 + or -

Question 13

how to calculate confidence interval?

Answer 13

Z score x SD/ square root of sample size

Question 14

How to calculate NNH?

Answer 14

Harm indicates change

1/exposure - control

Question 15

how to calculate NNT?

Answer 15

Determine baseline to see how it improves

1/control - exposure

Question 16

What is absolute risk?

Answer 16

Control - exposure

Question 17

What is absolute risk increase?

Answer 17

AKA attriutable risk

Exposure - control

Question 18

How does PPV change with prevalence increase?

Answer 18

Increases

Question 19

How does NPPV change with prevealence increase?

Answer 19

Decreases

Question 20

How is standard deviation calculated?

Answer 20

(X - mean)2 / sample size

Question 21

How is standard error calculated?

Answer 21

Standard deviation/ square root of sample size

Question 22

What is the z value?

Answer 22

Number of standard deviations above or below value

Question 23

What is the z score for 50% CI?

Answer 23

0.67

Question 24

What is the z score for 90% CI?

Answer 24

1.645

Question 25

What is the z score for 95% CI?

Answer 25

1.96

Question 26

What is the z score for 99% CI?

Answer 26

2.576

Question 27

What does 1 standard deviations man?

Answer 27

Contains 68% of data

Question 28

What does 2 SD mean?

Answer 28

Contains 95% of data

Question 29

What does 3 SD mean?

Answer 29

Contains 99.7% of data

Question 30

How to calculate confidence interval?

Answer 30

Z value x SD/ square root of sample size

Question 31

What is the crude mortality ratio?

Answer 31

Observed/expected death per 1,000

Question 32

What is indirect standardisation?

Answer 32

Specific population x standard mortality rate= x per1,000

Question 33

What is the standardised mortality ratio?

Answer 33

Indirect standardisation/ expected deaths

Question 34

What is direct standardisation?

Answer 34

Two populations are added together to get total size then: Population size of both x age specific mortality rate per 1,000

Question 35

What is NNH?

Answer 35

Looks at exposure so 1/ exposure - control

Question 36

What is NNT?

Answer 36

Looks at baseline so 1/control - exposure