Z-scores are useful because a) z-scores indicate a person's ...

[hbsimmons88]

Z-scores are useful because
 
  a) z-scores indicate a person's standing as compared to the group mean
   b) z-scores can be converted to percentiles (assuming a relatively normal distribution)
   c) z-scores are usually positive
  d) both a and b

Question 2

Item difficulty refers to
 
  a) item complexity
   b) item obscurity
  c) the number of people who answer an item correctly
  d) all of the above

[sylvia]

Answer to Question 1

D

Answer to Question 2

C

[hbsimmons88]

Excellent

[lindahyatt42]

Thanks for the timely response, appreciate it