Statistical tests - A-level Flashcards
when is Mann Whitney U used
-unrelated data (independent groups)
- ordinal data
-test of difference
how is the data used in Mann Whitney U
in a table of ranks
what is a table of ranks in Mann Whitney U
lowest is given a rank of 1. if multiple data points are the same value the positions they would be are added and mean is calculated
how can ranks in Mann Whitney U be shown
frequency table
what is the value of u in Mann Whitney U
calculated and is the smaller of the values
how is Mann Whitney U seen as being significant
if the value of u is less than the critical value so the null hypothesis can be rejected and alternative hypothesis accepted
when is Wilcoxon used
-looking for a difference
-related design (repeated measures)
-ordinal data
how is ranking used in Wilcoxon
-done between difference in the two sets of data (signs are ignored during ranking)
-if the difference is 0 the data is not included in the ranking and is deducted from the N value
what is the T value in Wilcoxon
calculated value
how is the T value calculated in Wilcoxon
sum of the less frequent sign
how is Wilcoxon seen as significant
is the calculated value of T is less than the critical value the null hypothesis can be rejected and the alternative hypothesis accepted
is Mann Whitney U and Wilcoxon parametric tests
No, they are non-parametric tests
when is an unrelated t-test used
-looking for a difference
-interval data
-unrelated data (independent groups)
-criteria for parametric test must also be filled
what is the criteria for a parametric test
-level of measurement is interval
-normal distribution
-homogeneity of variance (as standard deviations of both groups are similar)
table of data in an unrelated t-test
-calculate sum of scores for A
-repeat for B
-square each value in the A group and calculate the sum of the squared values
-repeat for group B
what is the calculated value in an unrelated t-test
t value
when is an unrelated t-test significant
if the calculated value of t is greater than the critical value the difference is significant and the null hypothesis can be rejected and alternative hypothesis can be accepted