Example of 2-Sample t

A healthcare consultant wants to compare the patient satisfaction ratings of two hospitals. The consultant collects ratings from 20 patients for each of the hospitals.

The consultant performs a 2-sample t-test to determine whether there is a difference in the patient ratings between the hospitals.

Open the sample data, HospitalComparison.MTW.
Choose Stat > Basic Statistics > 2-Sample t.
From the drop-down list, select Both samples are in one column.
In Samples, enter Rating.
In Sample IDs, enter Hospital.
Click OK.

Interpret the results

The null hypothesis states that the difference between ratings for the two hospitals is 0. Because the p-value is 0.000, which is less than the significance level of 0.05, the consultant rejects the null hypothesis and concludes that the ratings for the two hospitals differ.

Method

μ₁: population mean of Rating when Hospital = A
µ₂: population mean of Rating when Hospital = B
Difference: μ₁ - µ₂

Descriptive Statistics: Rating

Hospital	N	Mean	StDev	SE Mean
A	20	80.30	8.18	1.8
B	20	59.3	12.4	2.8

Estimation for Difference

Difference	95% CI for Difference
21.00	(14.22, 27.78)

Test

Null hypothesis	H₀: μ₁ - µ₂ = 0
Alternative hypothesis	H₁: μ₁ - µ₂ ≠ 0

T-Value	DF	P-Value
6.31	32	0.000