Ahhhh.....so you have MULTIPLE respondents. That's better. And the additional details are good.
But what isn't clear (at least to me) is exactly what you want to measure, and how. If you ask a bunch of people "How much do you think your income will go up (or down) next year?" then you do not have any way to measure their certainty or uncertainty about that change. e.g., A person could be planning to retire, and know pretty clearly what his/her income will be the next year, let's say it's down by 50%. So, there's a big change in income, but a fair degree of certainty about it. OTOH, if you do grant funded research (as I do) then you can expect that your income next year will be very similar to this year, but be very uncertain about it (if that grant doesn't get funded, income may drop a lot)..... So, what is it you want? Degree of certainty about income? Expected change in income? Or what? HTH Peter Peter L. Flom, PhD Assistant Director, Statistics and Data Analysis Core Center for Drug Use and HIV Research National Development and Research Institutes 71 W. 23rd St www.peterflom.com New York, NY 10010 (212) 845-4485 (voice) (917) 438-0894 (fax) >>> [EMAIL PROTECTED] 3/23/2004 1:34:21 AM >>> I thank Dennis, Gordon, and Jay for their kind response. Apparently, my question is a lot more confusing than I thought, to the effect that Bob Wheeler felt that I intentionally over formulated the problem. I didn't, Bob. Here I'd like to give a precise statement of the problem at hand, and I would like to invite further suggestions. Given the suggestions of Dennis, Gordon, and Jay, I have a feeling that maybe what I am trying to do asks too much from the data. You'll be my judge. I have a survey dataset which has the information of the respondents' actual incomes in year 1, and the survey question also asks the respondents to rate their expected income in the following year after the interview. Their answers are recorded in the scales of "increase by less than 10%", "increase by 10% to 20%", etc.. What I am trying to obtain is a measure of "income uncertainty" or "income variability" perceived by the respondent at year 1, which I labeled "expected income variance". A bad term, may be. So, I stated the problem in my previoius posting as if the individual has income 100 in year 1, and expected to have income between 110 and 120 in year 2. Then I ask how to calculate the "income variance" (confusing term). Ideally, the income variance should measure the variability of incomes in year 1 and year 2. Now, if I have the individual's "actual income" in year 1, 2, 3, ..., I would have no problem calculating the income variance: simply calcualting the variance of those numbers. What I could not figure out is that in the case I have only 2 observations and one of which is an "expected" "range" of income, how could I calculate the corresponding income variance? Many thanks in advance, Eddy . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . ================================================================= . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
