Hi there,

I have a data frame DF of over 600 people's short term trade data in time
order. Below is the simplified structure of the data.

         id     invest     payout
[1]      1  10               -1
[2]      1          33           33
[3]      1  20               -5
[4]      2          200          33
[5]      2          33        -20
[6]      3           5          -5
[7]      3  5        -5

id is each person's id. Each person have invested many times in the sampling
period, in temporal order.

What I want to check is the correlation between invest and payout.

1. How do I run the regression for each person, with the "invest" being
devided by the mean or medium of the person's "invest"?
2. How do I plot a graph with y axis being invest/mean(invest) and x axis
being payout, all 600 people's dots superimposed on one graph?

I tried to use

for (i in 1:(dim (DF)[1]-1))
 {
if (DF[i,1]=DF[i+1,1])   id.lm <- lm(invest ~ payput, data=DF)
}

But I don't know how to superimpose graphs onto each other.

Thanks a lot!

Su

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