Running lotteries in DirectRT or Medialab

Hi, I wanted to conduct a study in which participants have to simulate investing in the stock market. Here is the study design:

1) Participants are asked how much they would invest in three different companies and have to type in dollar amounts within a given range (using either fill in the blanks in Medialab or text entry in DirectRT).

2) The 3 companies have different probabilities of giving a profit or a loss (e.g., Company 1 has 50% of doubling the investment and 50% chance of losing it all). Using a random number generator, each Company's outcome is computed and participants are given their total returns of the investment.

I can think of a way to do these random number computations using the Medialab Responses.xls file, but once participants’ total return is computed in Responses.xls, I don't how I can ask Medialab to display the total returns computed in Responses.xls to participants. Is there any way to do this?

If this can’t be done in Medialab, I know in DirectRT, is there a way to use people's response to a previous question (using “=rownumber”). Can I embed participants’ previous response in an Excel function and display the output of the Excel function?

For example, if participants entered the amount they wanted to invest in Companies A, B, and C in rows 1, 2, and 3, can I use an Excel formula like this to compute their total investment returns: =if(randbetween(0,1)<.5,Row1Amount*2,0)+if(randbewteen(0,1)<.67,Row2Amount*1.5,0)+if(randbetween(0,1)<.33,Row3Amount*3,0)

Basically I am not sure how to embed participants’ previous responses in the Excel formula.

I would greatly appreciate any help possible.

Thanks a lot,
Krishna

Before answering your first question, I thought it might be helpful to present the following: [URL]http://www.empirisoft.com/support/showpost.php?p=1952&postcount=2[/URL]
Given your equation it doesn't quite matter too much to switch out the randbetween function with RAND(); however it may help to know that the prior doesn't quite work as of now.

In regards to your question, MediaLab can reference any variables on the responses.xls grid by using angle brackets within other locations of the experiment. More information can be found here:
[URL]http://www.empirisoft.com/medialab/help/calculated_scores.htm[/URL]

To answer your second question - currently DirectRT does not support excel functionality in the manner presented; however we hope to eventually have our 2010 version working with this feature.
The first strategy should work. If you need help programming this experiment, feel free to let us know.

By using both custom items and MediaLab's advanced features, just about anything can be created.