cronbach alpha: Scale reliability coefficient differs from test score alpha

[Steven Saxonberg]

In conducting Cronbach Alpha with STATA 14 the "scale reliability coefficient" differs from the "test score alpha" -- how is this possible? This is the result I get:

alpha famsuffers preschsuf wrkwarm

Test scale = mean(unstandardized items)

Average interitem covariance: .7442413
Number of items in the scale: 3
Scale reliability coefficient: 0.7604

. alpha wanthome preschsuf wrkwarm, generate(suffering) item label

Test scale = mean(unstandardized items)

item-test item-rest interitem
Item | Obs Sign corr. corr. cov. alpha Label
-------------+----------------------------------------------------------------------------------------------
wanthome | 20390 + 0.7496 0.4078 .5971789 0.6054 what women really want is home and kids
preschsuf | 20963 + 0.8266 0.5428 .3380404 0.3989 preschool children suffer if the mother
| works
wrkwarm | 21167 + 0.7235 0.4041 .6565875 0.6081 working mother can have a warm
| relationship with her children
-------------+----------------------------------------------------------------------------------------------
Test scale | .5310093 0.6440 mean(unstandardized items)
------------------------------------------------------------------------------------------------------------

[William Lisowski]

Subsequently reposted, with an initial response at this time, at https://www.statalist.org/forums/for...st-score-alpha