Maths Flashcards
1
Q
How do you calculate standard deviation?
A
Square root of (sum of(x-x̅)^2/n-1)
2
Q
How do you find the median for grouped data?
A
l+w (n/2)-cf/2
3
Q
Define sample:
A
Subset of population
4
Q
Define population:
A
Complete set of individuals of interest.
5
Q
Define inferential statistics:
A
method of making statements about pop based on sample findings.
6
Q
What is simple random sampling?
A
- Probability sampling
- All units have the same probability of selection
- Need sampling frame
7
Q
What is stratified random sampling?
A
- 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.
8
Q
How do you calculate the interval of a sample?
A
Interval = sample mean +- 2(sample sd/root n)
