Calculating PED with real-life data

[Schnee]

Hey guys, I just want to confirm that I'm doing this right with real-life sales figures.

The data available are annual revenues and annual units sold, therefore I will be finding unit price from annual revenue/annual units sold. The data provides figures for 10 years. Then I'll apply the equation PED=%change in Qd/%change in price between every two years, finally I'll find the average of the 9 PEDs found over an interval of 10 years.

...Or is it better to just use the data from the first year and the last year?

Of course I know that the results are going to seem odd (in fact when I tried it they turned out POSITIVE...) unless we live in a perfectly programmed world. That brings up another question, how can other factors such as change in income, population etc. (you know, the non-price determinants) be accounted so that the calculated PEDs are more accurate? Or is there no numerical way of doing so? Thanks, it'll be a great help~

[CkyBlue]

Is this a case study? If I were you I'd just make things simple for myself if you are not analyzing any trends in economic activity and just use the data from the first and last year.

Wow... positive results? That doesn't even make sense The only time (theoretically, [my knowledge only bound to the IB syllabus]) that the demand curve is positively sloping is when the thing/product/good/widget under consideration is a Veblen or Giffen good-the latter of which is arguably non-existent. Check you numbers and your formula again and hope you get it right the second time.

The 2012 syllabus did not stress graphs and numbers much, so I am almost out of things to say. I know the new syllabus introduces "numbers" to future candidates a bit more, and there are even functions to work with, but I am fairly certain they will not emphasize on something complex as you are mentioning (incorporating factors of demand or PED calculations). The IB economics course is a very conceptual and theoretical learning environment, even now. Just stick within what is taught and don't try to do something dangerous- because you might hurt yourself