Calculate average difference between dates when they first appear in dataset

Hi All,

I have a large dataset with dates of visits and dates of purchases for each customer. The data looks like this:

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I would like to know the "average number of days between first visit and first purchase" for every year (I know data are between 2004-2014 only).

So, in the case of customer no.10 she made a first visit on 17-06-2011 but she made her first purchase on 18-02-2012 -> 246 days later. I would like to know the average days of difference between first visit and first purchase by year. So, I want to be able to say "The time that passed between first visit and first purchase for all customers in 2012 was X amount of days; in 2013 it was Y days, etc.". Remember, each customer has multiple rows of visits and purchases...

I am open to any suggestion! Thanks!!

Hi,

Would you attach the workbook with a larger sample of data. No need to include all years back to 2004 but few dozen representative rows from 2014 would be useful. Experience tells me that the actual data used by someone is often slightly different to the very small subset that appears in the text of a post.

Originally Posted by Billaus

That's actually copy-pasted from the dataset. All data look exactly like that

Hi,

Would you nevertheless upload the workbook as requested. Be sure to include several customers and all permutations of data layouts. Experience here through the years tells me that what starts out as a simple text representation of data is often little use when it comes to applying a solution based on that text to the actual workbook itself. You need to help us to help you.

Attached!

Actually, an even better alternative (if easier) would be to generate a new variable (new column) that gives me the difference between first visit and first purchase for each customer. That means I'd have one row with that value and all other rows for that customer as NA.

Whatever easier...

Thanks!