Most PI firms track cost per lead and cost per signed case by vendor. Very few track what happens after the case is signed — specifically, how many cases from each source are withdrawn, dismissed, or otherwise never produce revenue. That downstream metric is case attrition rate by lead source. And it is one of the most revealing indicators of vendor quality that exists.
A vendor can deliver cases at an attractive CPC while producing a 35% attrition rate. Another vendor may cost more per signed case but deliver cases that settle at 92%. Without source-level attrition data, you cannot distinguish between the two — and your budget allocation suffers accordingly.
What Counts as Attrition
Before you can measure attrition, you need a clear definition. Case attrition includes any signed case that exits your pipeline without producing fee revenue. The three primary categories are:
- Client withdrawal: The client disengages, stops responding to communication, or formally withdraws from representation. This is the most common attrition type for cases from digital lead sources.
- Firm dismissal: Your team determines the case does not meet liability, damages, or other viability thresholds after signing. This often indicates a gap between intake qualification criteria and actual case requirements.
- No-contact / unreachable: The client signed but was never successfully contacted after the initial intake process. This is particularly common with high-volume digital aggregators where the client may have submitted inquiries to multiple firms simultaneously.
Each category tells a different story about lead quality. High client withdrawal rates suggest low commitment or mismatched expectations. High firm dismissal rates suggest poor pre-screening. High no-contact rates suggest the lead was never genuinely interested in representation.
Building the Data Infrastructure
Tracking attrition by source requires connecting two systems that most PI firms keep separate: your marketing attribution data (which source generated each lead) and your case management data (what happened to each case after signing).
Tag every lead with its source at first contact
Use UTM parameters, call tracking numbers, or vendor-specific identifiers. The source tag must persist through the intake process and into your case management system. If the tag drops during handoff, you lose attribution.
Define case disposition categories in your CMS
Create standardized disposition codes: Settled, Withdrawn (client), Dismissed (firm), No-Contact, and Pending. Avoid vague categories like "Closed" or "Inactive" that obscure the reason for exit.
Record disposition with the original source tag intact
When a case reaches final disposition, the source attribution must still be attached. This is where most tracking systems break — the marketing team tags the lead, but the case team closes the file without referencing the source.
Build cohort-based reporting by sign date and source
Group cases by the month they were signed and the source that generated them. Track the disposition of each cohort over time. A January 2025 cohort from Vendor A might show 85% settled, 10% withdrawn, 5% dismissed by Q3 2026.
Calculate attrition rate per source per cohort
Attrition Rate = (Withdrawn + Dismissed + No-Contact) / Total Signed Cases from Source. Run this for each vendor, each month, and track the trend over time.
The Cohort Methodology
Attrition is not a point-in-time metric. It unfolds over months. A case signed in March will not have a final disposition until 6 to 18 months later, depending on case complexity and your firm's workflow. Measuring attrition requires a cohort approach — tracking groups of cases from the same time period through their full lifecycle.
Here is how it works in practice. Every month, you have a new cohort of signed cases from each source. At 90 days, you can measure early attrition — cases already withdrawn or marked no-contact. At 6 months, you have a clearer picture. At 12 to 18 months, most cases have reached final disposition and your attrition rate stabilizes.
The 90-day early attrition rate is your leading indicator. If a vendor's cases are showing 20% attrition within the first 90 days, the final attrition rate for that cohort will almost certainly be higher. Use early attrition to flag problems quickly, even before final disposition data is available.
What the Data Reveals About Vendor Quality
Once you have source-level attrition data, patterns emerge quickly. Here is what a typical vendor portfolio looks like when attrition is measured for the first time.
| CPC | Attrition Rate | Primary Attrition Type | CPVC | |
|---|---|---|---|---|
| Vendor A (Referral Network) | $4,200 | 8% | Firm dismissal | $4,565 |
| Vendor B (Google Ads Agency) | $3,100 | 18% | Client withdrawal | $3,780 |
| Vendor C (TV/Radio) | $2,800 | 26% | Client withdrawal | $3,784 |
| Vendor D (Lead Aggregator) | $2,200 | 38% | No-contact | $3,548 |
| Vendor E (Social Media) | $2,500 | 42% | No-contact | $4,310 |
Several patterns are worth noting. Vendor A has the highest CPC but the lowest attrition — referral cases come pre-screened, and the small amount of attrition is firm-side dismissal, not client disengagement. Vendor D has the lowest CPC but 38% attrition, mostly no-contact — the cases were cheap to acquire because many of the leads were never genuinely engaged.
Vendor E is the outlier. Despite a moderate CPC, its 42% attrition rate produces the second-highest cost per viable case in the portfolio. On a CPC basis, Vendor E looked like a reasonable investment. On a CPVC basis, it is the most expensive source after Vendor A — without delivering the case quality that justifies Vendor A's premium.
Incorporating Attrition Into Vendor Reviews
Attrition data changes the vendor review conversation. Instead of evaluating vendors solely on volume and CPC, you can now assess the full cost of what they deliver.
Here is a framework for integrating attrition into your quarterly vendor review:
- Report CPC and CPVC side by side.Make the gap visible. If a vendor's CPVC is more than 25% above their CPC, attrition is a material issue that needs to be addressed.
- Break down attrition by type. High client withdrawal suggests expectation mismatch — the client did not understand what they were signing up for. High no-contact suggests lead quality issues at the source level. High firm dismissal suggests screening gaps in your intake process.
- Trend the data over time. Is attrition improving, stable, or worsening? A vendor with rising attrition deserves a direct conversation about lead quality. A vendor with declining attrition deserves credit — and potentially more budget.
- Set attrition targets in vendor SLAs. If your portfolio average is 22% attrition, set a target of 20% or below. Vendors that consistently exceed the target need a performance improvement plan with a defined timeline.
Early Warning Signs to Watch
You do not need to wait 12 months for final disposition data to detect attrition problems. These leading indicators are available within the first 30 to 90 days:
- First 7 days: Failure to reach the client after three contact attempts. Sources with high 7-day no-contact rates typically produce the worst final attrition numbers.
- First 30 days: Client has not returned signed engagement documents or provided medical authorization. This is a strong early signal of eventual withdrawal.
- First 60 days: No medical records obtained or initial case assessment not completed. Cases stalled at this stage have attrition rates 3 to 4 times higher than cases that are progressing normally.
- First 90 days: Attorney review determines case does not meet minimum damages or liability threshold. This indicates a screening gap between intake criteria and case requirements.
Track these milestones by source. When a vendor's cases consistently miss early milestones, you have actionable data long before the final attrition number is calculated.
From Measurement to Action
Measuring attrition by source is not the goal. The goal is making better decisions with the data. Here are the three decisions that source-level attrition data directly informs:
- Budget reallocation: Shift spend from high-attrition sources to low-attrition sources, even if CPC increases. The CPVC math almost always favors this move.
- Vendor accountability: Share attrition data with vendors. The best vendors want to know — it helps them improve their targeting. Vendors who resist the conversation are telling you something.
- Intake process improvement:If attrition from a specific source is driven by firm dismissal, the issue may be your intake criteria, not the vendor's lead quality. Tighten qualification before signing, and attrition drops.
RevenueScale's Case Analytics tracks case disposition by lead source automatically, calculates source-level attrition rates in real time, and surfaces early warning indicators — so you can see vendor quality issues in weeks, not months.