The decision — prop, eVar, or both?
Purpose: Run the decision tree for every candidate dimension to choose correctly.
Who this page is for
| Audience | Why it matters to you |
|---|---|
| Architects and leads | This is the SDR design conversation |
| Implementation engineers | Use this tree for every variable you build |
The decision tree
Run every candidate dimension through this:
Does this value need to receive credit for a conversion
that happens on a LATER hit?
│
├── YES ──► eVar. Now choose expiry:
│ How long is the influence window?
│ ├── Within the session ──────► Visit
│ ├── Until a specific action ─► Expire on event
│ ├── Days/weeks (marketing) ──► Custom N days
│ └── Permanent trait ─────────► Never
│
└── NO ───► Do you need pathing (next/previous page flow)?
│
├── YES ──► prop (with pathing enabled)
│
└── NO ───► Do you need it for hit-level
breakdowns or debugging?
├── YES ──► prop
└── NO ───► Don't collect it.Should I set both prop and eVar for the same thing?
The old orthodoxy was yes — duplicate everything. This came from an era when props and eVars had genuinely different reporting capabilities and slots were plentiful.
The current answer: usually no. Duplicate only when you have a concrete need for both behaviours — most commonly page name, where you want the prop for pathing and an eVar for attribution.
Duplicating everything burns slots, doubles your SDR maintenance, and doubles the surface area for the two to drift out of sync (which they will, and then you will spend a day working out which one is right).
Worked examples
| Dimension | Choice | Reasoning |
|---|---|---|
| Page name | prop and eVar | prop for pathing, eVar for attribution |
Site section (/member/, /employer/) | prop | Hit-level context, no attribution need |
| Internal search term | eVar, Visit expiry | Must get credit for what happens after the search |
| Search results count (0, 1–5, 6+) | prop | Describes the hit; you break search terms down by it |
| Form name | eVar, expire on submit event | Must get credit for the submission |
| Form step / stage | prop | Hit-level position in the flow |
| Form error message | prop (or list prop) | Describes this hit; multiple errors possible |
| Member persona (Member/Employer/Adviser) | eVar, Visit expiry | Segments everything in the session |
| Login status | eVar, Visit expiry | Segments everything in the session |
| Campaign code | eVar, custom 30-day expiry | Classic attribution window |
| Chatbot topic | eVar, Visit expiry | Should get credit for downstream call deflection |
Exercise
For examplesuper.com.au, decide prop vs eVar for each of these and justify in one sentence:
- The award badge shown in the footer
- Whether the user came from the chat icon
- The PDF filename downloaded
- The state selected in the locations map