Statistical techniques Flashcards
What are the advantages and disadvantages of mean, median, mode and range
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
What are the advantages an disadvantages of Spearman’s rank
- Define a clear relationship between 2 things with significance
- Less sensitive to anomalies
- Don’t provide a casual link
- TIED RANKS effect validity
- Subject to human error
What are the advantages and disadvantages of Standard Deviation
- Shows the extent to how data is clustered around the mean, telling us if the mean is reliable (low SD)
- Subject to human error
68%, 95% and 99.7%
What are the advantages and disadvantages of chi squared
- Identifies difference between expected and observed
- Subject to human error
What are the steps for carrying out a chi squared test
- identify a null (no relation) and an alternate hypothesis
- Calculate X^2
- Test to significance table
- Conclude
What is the equation for expected frequencies in a grouped table
row total x column total
DIVIDED BY
overall total
How do you calculate expected frequency
total divided by number of columns
What is the equation for chi squared
x^2 = sum of (O-E)^2 divided by e
What is the equation for SD
Root (x-mean)^2 divided by n
What is the equation for spearmans rank
1- 6Ed^2 divided by n^3-n
What to do in spearman’s rank if values repeat ?
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
