Question

The accompanying data on response time appeared in the article "'The Extinguishment of Fires Using Low-Flow Water Hose Streams-Part II" (Fire Technology, 1991: 291-320).

Good visibility

.43 1.17 .37 .47 .68 .58 .50 2.75

Poor visibility

1.47 .80 1.58 1.53 4.33 4.23 3.25 3.22

The authors analyzed the data with the pooled t test. Does the use of this test appear justified? (Hint: Check for normality.

The z percentiles for n=8 are -1.53, -.89, -.49, -.15 , .15, .49, .89, and 1.53.)

Short answer

Any test which requires normality should not be used.

Step-by-step solution

To analyzing the   t test appear justified

It appears that the good visibility does not come from a normally distributed population-based on the normal probability plot given below. For the pooled t test assumption of normality for both populations is needed. However, only the poor visibility satisfies that. Thus,

any test which requires normality should not be used

Step 2:To analyzing the   t test appear justified

To analyzing the  t test appear justified