Statistical test

Students t-test / unpaired t-test

  • for looking at average differences between independent groups

  • e.g. average height of children in yr 10 and avg. height of children in yr 9

Ho = there is no significant difference between the heights of yr 9 and 10 students

H1 = there is a significant difference between the heights of yr and 10 students

  • calculate the degreed of freedom = (n-1)+(n-1)

  • if the value of t at the value of the answer is below the threshold, the difference is not significant and you can accept the null hypothesis

Assumptions:

  • we have two independent groups

  • unbiased sample

  • sample sizes roughly equal

Paired t-test

  • looking at the differences between two non-independent groups

  • e.g. looking at blood pressure of a set of patients on monday then on tuesday (same set of patients)

degrees of freedom are (n-1)

Assumptions:

  • the variable is continuous

  • unbiased sample of pairs