A1 Stats

Question 1

Define Population

Answer 1

All of the individual items which are of interest in the given situation

Question 2

Simple Random Sampling

Answer 2

• Take a random selection from the population to use a sample.
• The entire population must be known and have an identifier.
• Each sample will be different and will contain some bias.S

Question 3

Stratified Sampling

Answer 3

• The parent population has clear subgroups, each subgroup can be proportionally represented:

(Subgroup Num/Population Num) x Sample Size

Question 4

Quota sampling

Answer 4

• Similar to stratified sampling, although thw quota

Question 5

Box Plots

Answer 5

Shows the spread of data, from min to max value, lower quartile, upper quartile, and median.

Question 6

Describe frequency polygons and what they’re commonly used for

Answer 6

• A line graph that plots frequency on the y axis against the value of the data on the x axis.
• Used to represent group data, where the midpoint is used.

Question 7

Formula for midrange of data

Answer 7

Max + Min / 2

Question 8

What is IQR and median used for?

Answer 8

A measure of spread and central tendency.

Question 9

What is standard deviation and mean used for?

Answer 9

A measure of how dispersed data is in relation to the mean, which shows central tendency.

Question 10

How is standard deviation related to variance?

Answer 10

Variance is the square root of standard deviation.

Question 11

Formula for standard deviation

Answer 11

S^2 = (Σx² / n) - x̄²

Question 12

How to find outliers using IQR

Answer 12

• 1.5 x IQR below Lower Quartile
• 1.5 x IQR above Upper Quartile

Question 13

Outliers using standard deviation

Answer 13

• Values more than 2 standard deviations from the mean.

Question 14

Define Critical Region

Answer 14

The set of values for which the null hypothesis is rejected.

Question 15

Define Critical Value

Answer 15

The borderline value(s) for which the null hypothesis is rejected.