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Syntax

GROUP_PREVIOUS(<any>;[<number>])

 value: series value

k: lag

Description

Returns the value of the set k'th previous record in series. This can be used for introducing a lag for time series analysis and/or computing autocorrelation.

This is a group series function.

Example

Given the following data:


First create a group, e.g. GROUPBY(#RawData!Groups)


Then use the GROUP_PREVIOUS(#RawData!Number), and the result will show the previous record's value in relation to the GROUPBY() column.

 

Example 2

The following example illustrates how to compute the time a user has spent on a web site.

Given the following data:


First create a group, e.g. GROUPBY(#RawData!Session)


Next sort your timestamp in ascending order, e.g. GROUP_SORT_ASC(#RawData!TimeStamp)


Next use the GROUP_PATH(#RawData!url), and the result will show paths for all values of the column in ascending order in relation to the GROUPBY() column.


Next use GROUP_PREVIOUS(#RawData!TimeStamp)


Finally use DIFF(#Sheet1!Ascending_TimeStamp;#Sheet1!Previous_TimeStamp) to subtract the ascending TimeStamp from the Previous_TimeStamp to find how long the user spend on the url.

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