lesson 11 - Inferential Analysis Flashcards
Questions to ask when choosing statistical test
Is it a test of difference, a correlation or an association?
2) What design have I used? Independent measures or repeated measures/matched participants design?
3) What level of measurement have I used? Nominal, ordinal, interval, ratio?
4) Is the test non parametric or parametric?
How do ik if my results are significant or not
Spearmans Rho
Mann Whitney
Compare calculated statistical answer to critical value:
S Calculated value must be greater than or equal to the critical value
M Calculated value must be less than or equal to the critical value
When do we use spearman’s rho and what does it do
This is used when we wish to test a relationship or correlation between two variables.
The data should be ordinal (at least).
The data are in related pairs This is a non-parametric test
Spearman’s Rho calculates the strength of the relationship between the two variables e.g. if r is -1.0 this means there is a perfect negative correlation between two variables, and if r is +1.0 then this is a perfect positive correlation.
What does n stand for
Number of pps
What is d
Difference
When do u use mann whitney
This test is used when we are looking for a test of difference
This statistical test is used when we have an independent group design.
We also use this test when we have data that is ordinal (can be placed in rank order) or interval.
This test is a non-parametric test
What is Na
Number of pps in a smaller sample
What is nb
Number of pps in a larger sample
What is T
Sum of ranks in a smaller sample
When do you use chi squared
This test can be used for either a test of association or for a test of difference (that is why this is a special statistical test).
• We use chi squared (for a test of difference) when we have an independent measures design and are using nominal data in the form of frequencies or separate categories.
• We would also use chi squared if we are testing an association that might occur between two variables. Again, the data would be nominal and would use an independent measures design
• Chi squared is a non-parametric test
How do ik if my results are significance for chi squared and wilcoxon
Chi Squared
Wilcoxon signed ranks
Compare calculated statistical answer to critical value:
C Calculated value must be greater or equal to the critical value
W Calculated value must be less than or equal to the critical value
What does observed value mean
Numerical value calculated using a statistical test
What are degrees of freedom
Logically independent values in a table
When do you use a wilcoxon test
It is used to measure a test of difference
This test is used when a repeated measures design or matched participants design has been used.
The data must be ordinal
• Wicoxon is a non-parametric test
Steps of a wilcoxon
To work out the Wico On matched can design results, fisty you should calculate the sum of positive ranks
Then calculate the sum of the negative ranks
