Statistical Analysis & Data Interpretation Flashcards

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

Answer: 1/3

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

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

Answer: 1/2

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

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

Answer: Beta (Type II error)

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

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

Answer: 15

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

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

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

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

For the same underlying d', which method gives a higher expected proportion of correct responses?

Answer: 3-AFC test

3-AFC uses a simpler decision rule (pick the strongest) than the triangle test (pick the odd one), so it yields more correct responses at the same d'.

In a triangle test, what is the formula for the proportion of distinguishers (Pd) based on the observed proportion correct (Pc)?

Answer: Pd = (3Pc − 1)/2

Since Pc = Pd + (1 − Pd)/3, solving for Pd gives Pd = (3Pc − 1)/2.