Stats: Sample types and data

Question 1

What are the two types of non-random sampling?

Answer 1

Quota and opportunity

Question 2

Describe quota sampling.

Answer 2

The population is divided into groups that reflect the whole population, or people are selected to fill a quota

Question 3

Describe opportunity sampling.

Answer 3

Sample of first people available that fit the characteristics

Question 4

What is the difference between a census and a sample?

Answer 4

• A census measures every member of a population

- A sample measures a subset of the population

Question 5

Give an example of when a census is a bad idea?

Answer 5

• When the population is very large

- When the testing damages/destroys the population, e.g testing limits of equipment

Question 6

What are the 3 types of random sampling?

Answer 6

• Simple Random
• Systematic
• Stratified

Question 7

Describe Simple random sampling.

Answer 7

Every member of the population has a completely equal chance of being tested (e.g assigned numbers and a generator used)

Question 8

Describe systematic sampling

Answer 8

Each unit of a sample is assigned a number and are selected at regular intervals

Question 9

Describe Stratified sampling.

Answer 9

Random sample from strata groups

Question 10

What does ‘cleaning’ data mean?

Answer 10

removing anomalies/outliers

Question 11

What is the mode of data?

Answer 11

Value that appears most often

Question 12

What is the mean of data?

Answer 12

Sum of all values/ number of values

Question 13

What is the median of data?

Answer 13

Middle value when data is placed in order

Question 14

What is the range of data?

Answer 14

Largest value - smallest value

Question 15

What is a common definition of an outlier?

Answer 15

k(IQR) + Q3
or
Q1- k(IQR)

Question 16

What is the difference between continuous and discrete data?

Answer 16

Continuous = data can take any value in a given range e.g height
Discrete = data can only take certain values, e.g shoe size

Question 17

What is bivariate data?

Answer 17

Data which has pairs of values for two variables

Question 18

What is the difference between qualitative and quantitative data?

Answer 18

Quantitative = numbers
Qualitative = words

Question 19

What is the name of a line of best fit for a scatter diagram? What is it used to find?

Answer 19

• Regression of y on x

- Can only be used to find y from x, not vice versa

Question 20

What is the height of a histogram bar?

Answer 20

it’s frequency density

Question 21

What are the 4 conditions for binomial distribution?

Answer 21

1. There are a fixed number of trials
2. There are 2 possible outcomes
3. There is a fixed probability of ‘success’
4. The trials are independent of one another