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From |
Nick Cox <njcoxstata@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: generate a column of a summary statistic conditioning on the comparison of the values in two other columns |

Date |
Wed, 5 Dec 2012 17:55:01 +0000 |

-egen- is the wrong place to look for this. You need to drill down to a more fundamental level. As a first stab at this bysort A (C) : gen mean_so_far = sum(B) / sum(B < .) except that it's previous values that you want. This doesn't really grapple with the difference between order date and delivery date. I expect you may need to combine order dates and delivery dates in a single date variable. See http://www.stata.com/statalist/archive/2012-11/msg01186.html for a similar (but not identical) problem. Nick On Wed, Dec 5, 2012 at 4:29 PM, David Peng <david.peng99@gmail.com> wrote: > I have a dataset with four variables, A, B, C, and D. A is a variable > representing the customer number. B is the main variable of interest > (in this case the dollar amount of a customer order). C is the date a > customer order was placed and D is the date the same customer order > was delivered. > > I would like to generate a column of summary statistic (let's say I > want the mean) in the table. Basically, for each customer order, I > would like to generate a mean value of the dollar amount for all of > the orders placed by a customer prior to the date the order is placed. > > For each observation (i.e., a cusomer order) in the data table, I > would like to get: > > bysort A: egen mean_dollar_amount=mean(B) if B is associated with a > delivery date D that is earlier than the order date C of the customer > order in question. > > > As an example, if I have an obervation representing an order placed by > the customer x with the order date of 12/30/2011, I would like to > generate the mean of the dollar amount for all of the orders that were > delivered earlier than the order date of 12/30/2011 for the order > mentioned above. I need a mean value like this for each observation > (i.e., customer order) in the data. > > Thanks in advance for your help. > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/faqs/resources/statalist-faq/ > * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: generate a column of a summary statistic conditioning on the comparison of the values in two other columns***From:*David Peng <david.peng99@gmail.com>

**References**:**st: generate a column of a summary statistic conditioning on the comparison of the values in two other columns***From:*David Peng <david.peng99@gmail.com>

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