This help page describes how eVars work as a dimension. For information on how to implement eVars, see eVars in the Implement user guide.
eVars are custom variables that you can use however you like. If you have a solution design document, most dimensions specific to your organization end up as eVars. See Dimensions overview for more information.
By default, eVars persist beyond the hit that they are set on. See the sections How eVars work and How eVars tie to metrics below for details on how eVar persistence operates on Adobe’s architecture. You can customize their expiration and allocation under Conversion variables in Report suite settings. The following image shows an example of eVar definitions in the Conversion variables interface:
The number of available eVars depends on your contract with Adobe. Up to 250 eVars are available if your contract with Adobe supports it.
The (upper or lower) case used in reports is based on the first value that you send in a given calendar month. The case can change depending on the reporting window and the case of an eVar value collected first during that time.
Each eVar collects data from the v1
- v250
query string in image requests. For example, the v1
query string parameter collects data for eVar1, while the v222
query string parameter collects data for eVar222.
AppMeasurement, which compiles JavaScript variables into an image request for data collection, uses the variables eVar1
- eVar250
. See eVar in the Implement user guide for implementation guidelines.
Since eVars contain custom strings in your implementation, your organization determines what the dimension items are for each eVar. Make sure that you record the purpose of each eVar and typical dimension items in a solution design document.
When you send data to Adobe Analytics, data collection servers translate the hit into a single row of data with hundreds of columns. Two columns are dedicated to each eVar; one for direct data collection, and the other for persisting values.
Under almost all circumstances, the post_evar
column is used in reports.
Success events and eVars are frequently defined at different times. The post_evar
column allows eVar values to tie themselves to events, showing data in reporting. Take the following visit for example:
A simplified version of the raw data would look similar to the following:
visitor_id |
pagename |
evar1 |
post_evar1 |
event_list |
---|---|---|---|---|
examplevisitor_987 |
Home page |
|||
examplevisitor_987 |
Search results |
cats |
cats |
event1 |
examplevisitor_987 |
Product page |
cats |
prodView |
|
examplevisitor_987 |
Cart |
cats |
scAdd |
|
examplevisitor_987 |
Checkout |
cats |
scCheckout |
|
examplevisitor_987 |
Purchase confirmation |
cats |
purchase |
visitor_id
column ties hits to the same visitor. In actual raw data, the concatenated values of visid_high
and visid_low
determine visitor ID.pagename
column populates the Pages dimension.evar
column determines the hits when eVar1 was explicitly set.post_evar1
carries the previous value, dependent on the variable’s allocation and expiration set under report suite settings.event_list
column contains all metric data. For this example, event1
is ‘Searches’, and the other events are standard shopping cart metrics. In actual raw data, event_list
contains a comma-delimited set of numbers with a lookup table tying those numbers to a metric.Tools in Adobe Analytics, such as Analysis Workspace, work off of this collected data. For example, if you pulled a report using eVar1 as the dimension and Orders as the metric, you would see a report similar to the following:
Internal search term (eVar1) |
Orders |
---|---|
cats |
1 |
Analysis Workspace pulls this report using the following logic:
event_list
values, and pick out all of the rows with purchase
in them.post_evar1
value.The resulting report shows each different value contained in post_evar1
on the left, and how many orders were attributed to that value on the right.
Since allocation and expiration determine what values persist, they are vital in getting the most value out of an analytics implementation. Adobe highly recommends that you discuss within your organization how multiple values for each eVar are handled (allocation) and when eVars stop persisting data (expiration).
post_evar
column.You can change eVar allocation and expiration under Conversion variables in Report suite settings.
Adobe recommends using eVars in most cases, supported through the following:
See prop for more comparisons between props and eVars.