Maths

Question 1

How do you calculate standard deviation?

Answer 1

Square root of (sum of(x-x̅)^2/n-1)

Question 2

How do you find the median for grouped data?

Answer 2

l+w (n/2)-cf/2

Question 3

Define sample:

Answer 3

Subset of population

Question 4

Define population:

Answer 4

Complete set of individuals of interest.

Question 5

Define inferential statistics:

Answer 5

method of making statements about pop based on sample findings.

Question 6

What is simple random sampling?

Answer 6

• Probability sampling
• All units have the same probability of selection
• Need sampling frame

Question 7

What is stratified random sampling?

Answer 7

• Population of different strata e.g. gender, ethnicity.
• Simple random sampling may miss out or overrepresent certain groups.
• Divide population into groups -> random sample from each (sampling frame needed).
• Group size proportional to actual pop size.

Question 8

How do you calculate the interval of a sample?

Answer 8

Interval = sample mean +- 2(sample sd/root n)