Originally Posted by
morgaine300
Well, straight off the top I can't answer your question, but so far no one else has touched it so... Whenever we did this type of thing (it was actually an opinion on some political issue or other, but based on the same sorts of demographics), I think we set up a joint probability table and conditional probabilities, and were not doing hypothesis testing of the sort you are doing.
What I can do is tell you the part that you're doing wrong. You're mixing up two sets of data. One is the salaries of all people surveyed, but then you're mixing into, on the same x line, only those who have higher than a high school education. Your x line is all the people surveyed because you're using data from the entire survey.
Working out the math, the only thing you've shown is the z score for ANYONE earning greater than 10,000. There isn't anything in there that accounts for the people having higher than a high school education. Do you see what I mean?
Ho and Ha have to be about earning more or less than something. What's the "something."?
I'm not sure, but I think you need to be maybe comparing a sample of +high school to the average of no more than high school, and see if it's actually 10,000 higher?
Also note that "10,000 higher" is actually not the 10,000 at the left side -- you're saying higher than people with no more that higher school. Somehow you've got to split these people up to compare them. i.e. what's average for no more than high school compared to more than high school? Earning $10,000 isn't the same as earning "10,000 more than something else."
That's not really totally an answer, but may help you get off thinking the right direction.
