Scenario: You develop 3 distinct user interfaces for a software application and want to determine which one leads to higher user satisfaction. You recruit participants and randomly assign them to interact with either interface A, interface B or interface C. After using the interface, participants provide ratings on their satisfaction on a Likert scale, which is converted to numbers from 1 to 9. Your data set contain the following variables:
user interface (A, B, C)
ratings (1 to 9)
You test normality of each of the groups using Shapiro Wilk and it returns the following p values: A: p = 0.006, B: p = 0.010, C: p < 0.001
Is there a significant difference in user satisfaction between the 3 different user interface designs?
To answer this question, the following test should be performed