0
$\begingroup$

I want to measure if the number of people who agreed on a likert scale (1 strongly disagree - 5 strongly agree), so responded with a 4 or 5 had a statistically significant increase from the previous year.

2 different groups were surveyed and they have different sample sizes but they were the same questions so I'm thinking 2 sample t-test, but I'm not sure if i should just run a t-test since I'm only concerned about people who disagreed or were neutral.

$\endgroup$
2
  • 1
    $\begingroup$ As you have formulated it, this appears to be a (simple, textbook) Binomial test of proportions. With a sufficient number of both 4/5 responses and 1-3 responses in both years, a t-test would be an adequate approximation. Is there some aspect of your data or objectives that would suggest otherwise? $\endgroup$
    – whuber
    Jun 17 at 17:21
  • 1
    $\begingroup$ Please do not vandalize your question. When you posted on SE, you gave up ownership of the content under CC BY-SA 4.0. If there are no answers, you may delete your own question (see here ): just click the faint gray 'delete' at lower left (your account needs to be registered for this). Otherwise, the thread will remain according to SE's rules. $\endgroup$
    – Sycorax
    Jun 17 at 22:17

1 Answer 1

1
$\begingroup$

Comment: Suppose that Gp 1 had 345 agreements (Likert 4 or 5) out of 1000 subjects and Gp 2 had 551 agreements out of 1500 subjects. Then as @whuber suggests prop.test seems appropriate. However, in R this test would not--even nearly--find a significant difference at the 5% level between proportions $0.345$ and $0.367$ "in favor." [Even if Gp 2 had a much larger proportion of Likert 5's.]

prop.test(c(345, 551), c(1000, 1500), cor=F)


       2-sample test for equality of proportions
       without continuity correction

data:  c(345, 551) out of c(1000, 1500)
X-squared = 1.3014, df = 1, p-value = 0.2539
alternative hypothesis: two.sided
95 percent confidence interval:
 -0.06058569  0.01591902
sample estimates:
   prop 1    prop 2 
0.3450000 0.3673333 

If you need a discussion using a t test, then please give an example of Likert-5 sample distributions for Groups 1 and 2. (There are several reasons why a two-sample Wilcoxon test might not work well.)

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.