This site is intended for healthcare professionals

Go to /sign-in page

You can view 5 more pages before signing in

T test (statistics)

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

  • unpaired t-test (also known as the student's t-test) and the paired t-test both assume that analysed data is from a normal distribution
  • unpaired t-test
    • applied to two independent groups e.g. diabetic patients versus non-diabetics
    • sample size from the two groups may or may not be equal
    • in addition to the assumption that the data is from a normal distribution, there is also the assumption that the standard deviation (SD)s is approximately the same in both groups



Mean (SD)

No diabetes

Mean (SD)

Mean difference

95% CI


Age (years)

68.8 (8.7)

73.3 (9.0)

4.2 (3.1, 5.3)

p <0.0001

Heart rate (bpm)

75 (15.0)

76.1 (14.9)

1.1 (-0.9, 3.1)

p 0.85

  • paired t-test
    • data is derived from study subjects who have been measured at two time points (so each individual has two measurements). The two measurements generally are before and after a treatment intervention
    • 95% confidence interval is derived from the difference between the two sets of paired observations


  1. Doctor (March 22nd 2005):33-35.

Related pages

Create an account to add page annotations

Add information to this page that would be handy to have on hand during a consultation, such as a web address or phone number. This information will always be displayed when you visit this page