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# Re: st: Draw an offer curve (supply curve)?

 From "Brian P. Poi" To statalist@hsphsun2.harvard.edu Subject Re: st: Draw an offer curve (supply curve)? Date Wed, 02 Nov 2011 16:05:05 -0500

```G. Dai wrote:
```
```By the way, is there any way to indicate the ID of the offered
quantity, that is the stairstep in the curve? Say, can we use
different colors to distinguish IDs in the offer curve?
thanks,

On Mon, Oct 24, 2011 at 7:07 AM, Brian P. Poi <bpoi@stata.com> wrote:
```
```G. Dai wrote:
```
```Dear all,
I have a dataset on real offering behavior and I want to draw an
offering curve (supply curve) from the data set.
One simple example of the data is following:

1       10                         99
2        23                        90
1        5                          50
4       30                         32
3       39                         10
2       30                          0
4       20                          0
3       20                          0

ID is the individual participating in the trade, and quantity_offered
is the quantity they can offer at the price of Price_asked.
We can see some individuals just ask zero price for some quantities,
while ask a higher price for extra quantities.  My object is draw an
offer curve (supply curve) from the data in an efficient way because
the dataset  is big.

Any suggestion is appreciated.
Thanks and have a great weekend!
```
```How about something like this:

. input id q p
1       10                         99
2        23                        90
1        5                         50
4       30                         32
3       39                         10
2       30                          0
4       20                          0
3       20                          0
end

. sort p                  // put data in ascending price order
. gen totalq = sum(q)     // running sum of total quantity offered
// for price <= p
. line p totalq, connect("stairstep")

```
```
I'm not sure there is a clear way to represent the ID's of the offered quantities, because the prices are not unique.  For example, three different sellers are all willing to sell units at a price of zero.  Who goes first?

That said, I have a minor correction.  I think the graph command should be

. line p totalq, connect("stepstair")     // not "stairstep"

Say I wanted to buy 100 units.  Then I would have to bid 10, not zero.

Brian P. Poi
Senior Economist
StataCorp LP

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