Statistical techniques

Question 1

What are the advantages and disadvantages of mean, median, mode and range

Answer 1

Mean - Measures the average of data and accounts all values, but it can be influenced by extreme values

Median - Gives no indication of spread but isn’t effected by extreme values

Mode - Only works well for grouped data

Range - gives a spread of data but no average an scan be influenced by extreme values

Question 2

What are the advantages an disadvantages of Spearman’s rank

Answer 2

1. Define a clear relationship between 2 things with significance
2. Less sensitive to anomalies
3. Don’t provide a casual link
4. TIED RANKS effect validity
5. Subject to human error

Question 3

What are the advantages and disadvantages of Standard Deviation

Answer 3

1. Shows the extent to how data is clustered around the mean, telling us if the mean is reliable (low SD)
2. Subject to human error

68%, 95% and 99.7%

Question 4

What are the advantages and disadvantages of chi squared

Answer 4

1. Identifies difference between expected and observed
2. Subject to human error

Question 5

What are the steps for carrying out a chi squared test

Answer 5

1. identify a null (no relation) and an alternate hypothesis
2. Calculate X^2
3. Test to significance table
4. Conclude

Question 6

What is the equation for expected frequencies in a grouped table

Answer 6

row total x column total

DIVIDED BY

overall total

Question 7

How do you calculate expected frequency

Answer 7

total divided by number of columns

Question 8

What is the equation for chi squared

Answer 8

x^2 = sum of (O-E)^2 divided by e

Question 9

What is the equation for SD

Answer 9

Root (x-mean)^2 divided by n

Question 10

What is the equation for spearmans rank

Answer 10

1- 6Ed^2 divided by n^3-n

Question 11

What to do in spearman’s rank if values repeat ?

Answer 11

If there are two values of lets say 16, you find the next two ranks which 16 would be (for example 7 and 8)

You add the 2 ranks it should be and then divided by 2 to get rank 7.5