Rarely, proton pump inhibitors (such as omeprazole) have caused vitamin B-12 deficiency. The risk is increased if they are taken every day for a long time (3 years or longer). Tell your doctor right away if you develop symptoms of vitamin B-12 deficiency (such as unusual weakness, sore tongue, or numbness/tingling of the hands/feet).
Stability reliability refers to the consistency of students' scores when a test is administered to the same students on two different occasions. Alternate-form reliability describes the consistency of students' performances on two different (hopefully equivalent) versions of the same test.
Z-scores are an example of standard scores as they are expressed relative to a mean of 0 and a standard deviation of 1. Another standard score is I.Q. which has a mean of 100 and a standard deviation of 15. The mathematical definition of the Z-score is.