S2L1 - Measurement Scales, Numbers, Rates, Ratios And Risk

Question 1

What are the three domains of public health

Answer 1

Health improvement
Health protection
Healthcare public health

Question 2

What is the purpose of statistics?

Answer 2

Infer information about a population from a sample.

Question 3

What qualities should a sample population have?

Answer 3

Representative
Unbiased
Precise

Question 4

What are the two main types of errors that occur in studies?

Answer 4

Chance/ random error.

• different results from samples by chance.
• random error reduced as the sample size increases as we are likely to have a better representation of our whole population

Bias/ systematic error

• Difference between true value and expected value.
• does not reduce as sample size increases

Question 5

What can we do to reduce chance/ random error?

Answer 5

Increase sample size as this increases precision and therefore reduces uncertainty

Question 6

What are sources of bias/systematic error?

Answer 6

1. Selection biases

2. Information biases

Question 7

How do selection biases occur?

Answer 7

Selection biases occur when:

• study sample not representative of entire population interest
• groups within a study may not be comparable. Study group different to control group
• healthy worker effect, workers healthier than general population