Coefficient alpha (”Cronbach’s alpha”) or tau-equivalent reliability

In this video, the coefficient alpha (also known as Cronbach's alpha) and the two assumptions it makes are explained. Also, five common misconceptions about alpha are uncovered and alternatives to coefficient alpha are introduced.

[cracrul]

Great, professor. Your videos have helped me understand many things that I have simply done mechanically. Thanks.

[kjoit]

After hours of making sense of what my textbook is saying, I finally understood, thanks to you!

[olgawodecka]

So helpful!! I spent hours trying to figure out what tau equivalence means and now I finally get it :)

[Break_down]

I think a lot of applied researchers see/hear the phrase "alpha underestimates reliability" and think that alpha is a good default because it is conservative in being careful to not overestimate reliability. However, getting a nearly acceptable .70 from a covariance matrix describing two orthogonal factors is scary (2:46). The total score of this scale could be a meaningless average between two unrelated constructs. As someone who does applied research, it was important for me to read the McNeish 2017 article and do my own simulation to see that alpha can actually overestimate reliability as well.