Exercise: Congestive heart failure, answer 5

Question 5: In terms of internal consistency, CHQ-C demonstrated a Cronbach's alpha of 0.95. What is Cronbach's alpha and how would alpha = 0.95 be interpreted?

Suggested answer:

Cronbach's alpha is a measure of how well the items form a coherent scale. Alpha estimates the correlation between the variable measured by the scale and the latent variable which we think the scale represents.

Alpha lies between 0, when the items are completely independent and there is no consistency at all, and 1.00, when the items are identical. High values of alpha are interpreted as a consistent and reliable scale.

We are usually looking for a value of alpha at least 0.7, preferably higher. Alpha = 0.95 is a very high value suggesting high inernal consistency and a reliable scale in the sense that it measures something.

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