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rounding zscores
Posted:
Jan 14, 1997 11:20 AM


Hello, All....
Having just submitted a response which was intended to answer the question of rounding, I now have one of my own.
I have not seen published any clear guidelines for rounding zscores. When computing a zscore, I tell my students, we round to two decimal places so that we can use the table of standard normal probabilities.
But when answering the question "what is the zscore such that P(Z<z) =.95" what is the rule? P(Z<1.64) = .9495 and P(Z<1.65) = .9505. Which is the correct choice?
Is there a different response when answering the question "What must a student score to be in the top 10%?" (I have told my classes that their answer should give a score which guarantees that P(X<x) is at least .9000.)
I could sure use some guidance....
Thanks in advance.
Bob
 Bob Barrier C. E. Jordan High School 6806 Garrett Road Durham, NC 27707
barrier@jordan.durham.k12.nc.us



