Props and eVar

[cathyw49544988]

I took some training classes and read some help pages and I still have question about those 2 types of variables:

1. For Props, they mentioned that it can hold path. I am wondering is that mean it can hold the path of visitor's journey. If I use prop to hold variable like URL, page name, then I will get the navigation reports ( like landing , exit, full path, next page etc ). Is this the meaning of path?

2. I read the document mentioned that the recent version, evar and prop are very close to each other. So for right now, which data I have to use prop, can nor use eVar? Please provide some examples

3. for eVar, they mentioned that it is a persistence variable which can be used to hold conversion related info. The interesting thing I saw was, we tracking a search page load as an event. we used a eVar to hold the search keyword. But in the evar report, for the keyword  against visitors, then 99% are unspecified. Then I noticed that all the visits has this evar, if the user didn't visit the search page, then eVar is a null value, then showed as unspecified. Shouldn't the eVar report only include the visits load the search page?

4. Actually I really hope I can know more about how internal of adobe worked? How the persistent worked? Then I will know how should I use my variable. For example, when a event fire, some variable and event data will be saved to adobe server. The thing is, how evar can persistently show all the data for the conversion( like first touch, last touch), do they have a special meta-data to side track? I am just thinking in a database view, how this data is joined to show the conversion report.

Thanks

[Alexis_Cazes_ · Accepted solution]

If you want to know how the data is stored and processed then the best way is for you to play with Data Feed. It is the most granular data that you can get.

Check all the columns you can get.

Check this section of documentation to see how the data and metrics are calculated.

This will allow you to understand the different layers of processing: Processing Order

Now in terms of prop and evar differences:

• Prop
  • Expire on hit (a hit is a row in a data feed). Cannot persist further than the hit. This means that if you want to attribute an event to a prop you need to do it in the same analytics server call
  • Only has linear allocation. So all metrics (events in data feed) that you apply to a prop reports will use linear allocation
  • Pathing can be enable on any props. This means that you can see the sequential order of the values that have been sent. For best result, the prop needs to be specified in all analytics server calls. If a server call is missing the value then it will count as an exit from the path.
  • You can also use a prop as a list prop to send multiple values but I prefer to use list variables as you can assign different allocations
• Evar
  • The expiration can be set to what you want: hit, visit, never, after x days, when a specific event is sent etc....
  • The allocation can be set to:
    • Most recent (last touch): the most recent values sent to this eVar will persist (see expiration), until expiration end or new value is set. When an eVar is set (via server call) it will be in its corresponding evar column in data feed. And the persisting value will be set in post_evar. If using processing rules then only post_evar will be set. To see instances of the evar chec post_event_list and check for corresponding numeric id of the evar.
    • First touch: the first value send via sever call will persist until expiration. Even if you send new value it will not overwrite first value sent. Reset at expiration
    • Linear: all values send via server calls will get credit for the event when sent.
  • You can also use merchandising evars. More complex and won't go in details here.
  • You can also set an evar as a counter evar.
  • More details

[marion33678522]

Hello Alexis !

Congrats on the great explanations !
I already knew all of that , but it's the first time I found a real abstract and short explanation.
It really helps understanding the data feed before explaining props and evars.

Cheers !

Mario

[frankd55973318]

When I comes to a Prop and a hit level eVar, what reason is there to use an eVar instead of a prop (other than having linear/participation options)?

Thanks.

[Alexis_Cazes_]

Use props:

• if your value is less than or equal to 100 chars. anything above will be truncated.
• if you want pathing
• if you only want to see linear allocation for any metrics
• if you want to use list prop feature

Use evar:

• If your value is more than 100 char but less than or equal to 250 characters. Anything above will be truncated
• If you want other allocation than linear, for example last.
• If you want to use merchandising eVars
• if you want to use numeric type for evars
• if you want to modify expiration at any point to anything other than hit

might be other use cases but only these ones come to my mind right now.

[marion33678522]

Are you sure you can have numeric evars ?

It seems to me that only event can be numeric - I though they could only be counter or text.

For exemple, I won't be able to calculate the Mean of this :

Visit 1   :eVar42 = 4

Visit 2   : eVar42 = 5

Visit 3   :eVar42 = 6

Number of visits = 3
eVar42 instances = 3
Mean of Evar3 = (4+5+6)/3

Cheers,

Mario

[cathyw49544988]

Alexis,

Could you please explain more about the " linear allocation "?

Thanks.

[Alexis_Cazes_]

marion33678522​

What I meant by numeric evars is Counter evars, sorry for the misunderstanding.

See these articles:

https://webanalyticsfordevelopers.com/2014/10/21/counter-evars/

Counter eVars [Inside Omniture SiteCatalyst] | Adobe

[Alexis_Cazes_]

You can find some documentation about allocation here:

Allocation

Say you have a visit with 5 pageviews, evar1 is last allocation and evar2 is linear:

Pages     Prop1     Evar1     Evar2     Order

1               a               aa          qq          0

2               a               bb          ww         0

3               b               cc          ee          0

4               c               dd          rr            0

5               d               ee          rr          0

6               e               ff            rr           1

Prop1 report

prop     order

a               1/6  + 1/6 = 2/6 = 0.333333

b               1/6 = 0.166667

c               1/6 = 0.166667

d               1/6 = 0.166667

e               1/6 = 0.166667

evar1     order

aa               0

bb               0

cc               0 

dd               0

ee                0

ff                   1

evar2     order

qq          1/6 = 0.166667

ww          1/6 = 0.16667

ee           1/6 = 0.16667

rr          1/6 + 1/6 + 1/6 = 3/6 = 1/2 = 0.5

Linear allocation means that all values that where sent prior the event get credit for the event. Each instance of a value get 1/n where n is the number of instance of values prior event

[marion33678522]

This linear and last allocation explanation on how evars work is great !

Im' gonna save it somewhere !

Keep the good teaching !

Cheers !

[cathyw49544988]

Alexis,

This is very helpful. I still have a very basic question. As you described:

Pages     Prop1     Evar1     Evar2     Order

1               a               aa          qq          0

2               a               bb          ww         0

3               b               cc          ee          0

4               c               dd          rr            0

5               d               ee          rr          0

6               e               ff            rr           1

In this case, we want to track event for order, you have a visit with 5 pageviews. So the order event is visit based. Is that the same as expired after a session?

So all the credit can be shared within this visit. I guess there must have another internal variable to track the unique visit info, correct?

Another question I have is, how to link Prop1, Evar1 and eVar2 with order event? From the example, we can see that the first 5 pageview without order. For example, Prop1 is URL, eVar1 is category and eVar2 is division ( something like this ), maybe we have those data from page load event. Then order event happen, in order to link the order with those 3 variables, I will need to setup those 3 variables when the order event fired. Is this correct?

Right now, I am trying to thinking thing like a table. Every time a rule fired, then a row  of data will be written to database. If I didn’t setup a variable within that image, then for that row, that variable will be null value. Is this correct? But for the session, visitor ID those info is tracking automatically, correct? If this is the case, then I will know each time, if I want my event to link with any variable, I will have to set up those variables in my rule.

Thanks

[Alexis_Cazes_]

Visitor ID is tracked automatically. There are different ways a unique visitor is identified. See doc for data feed​

By default the Adobe Analytics library should generate the unique visitor, so unless you send a custom one, you should not have to do anything.

Any event is hit based, it does not persist after the hit. For the event to be attributed to a value for an eVar or a prop then this value needs to be set in the adobe analytics server call.

Prop value do not persist after the hit (after the analytics server call), so if you want the order to be attributed to this value send you need to send it in the same hit or a hit prior the order in the visit.

For eVar it is can be different based on the allocation and expiration.

If the evar is set to expire to anything other than hit, then the value set in the evar will persist until expiration. Now the value that persist is directly tied to to allocation. If it is first alllocation, then the first value set in the evar will persist until expiration and all event sent while the value persist will be attributed to it. If it is last allocation then last value that was set will persist until expiration and same as for first all events will be attributed to it.

I would advise you to create a new post if you need more details as I think it differs from the initial question asked.

[saraht69310464]

Hi Alexis,

I read in this post that props can be associated with success events that occur later, and will be attributed according to the linear allocation principal.
However when reading the Adobe Help Comparing Props and eVars I read

• eVars can use success events as metrics. Props cannot.
• eVars are designed to report on conversion events, to show you which values are most successful in influencing visitors to reach your goals. Traffic variables (props) do not have this same functionality. However, you can view participation metrics if you configure your report suite correctly. Participation metrics allow you to see what prop values participated before a success event.

This seems contradictory to your example of linear allocation.

Can you help me understanding this?

Thanks,

Sarah

[Alexis_Cazes_]

Hi Sarah,

The article that you referenced seems to be confusing to be honest.

I would suggest you to read these articles when it comes to how values of success events are allocated based on the allocation selected:

Metric Calculations

Participation​

I think the article that you referenced fail to explain the importance of expiration and allocation in Adobe Analytics data processing. A prop which is a traffic variable will always expire on the hit and have linear allocation. That's it, which means that f you run a report and you want to know what is the true value of a success event is, you should not use a variable in the report that has linear allocation.

eVars when enabled by default will always have a last allocation (most recent) and I think 30 days expiration. As it has last allocation, when you apply a success event to this evar report, you will always get the true total for the specific evar value.