CSA Statistical Analysis & Data Interpretation 2

Question 1

In a triangle test, what is the probability that an assessor selects the odd sample purely by chance?

Accepted Answer

1/3

Answer

With three samples and one odd one, a guessing assessor has a 1-in-3 chance of being correct.

Question 2

What is the chance probability of a correct response in a duo-trio test?

Accepted Answer

1/2

Answer

The assessor picks which of two coded samples matches the reference, so guessing gives a 50% chance.

Question 3

When running a triangle test to show that two products are similar, which error rate needs the tightest control?

Accepted Answer

Beta (Type II error)

Answer

Similarity testing must limit the risk of missing a real difference, so beta is set small (and alpha is often relaxed).

Question 4

In a triangle test with 30 assessors at alpha = 0.05, how many correct responses are needed to conclude that a significant difference exists?

Accepted Answer

15

Answer

Binomial tables for p = 1/3 show 15 of 30 correct responses as the minimum for significance at alpha = 0.05.

Question 5

What does the Thurstonian d' (d-prime) value represent in discrimination testing?

Accepted Answer

A measure of sensory difference that does not depend on the test method

Answer

d' expresses the size of the perceptual difference in standard deviation units, so results from different methods can be compared.

CSA - Certified Sensory Analyst Practice Test