Evidence pack

AI agent assist (simulated)

IT service desk · 2025-01-06 to 2026-07-05 · 40 teams · 74,260 tickets · Owner: Head of IT Service Management
BEvidence grade
Agent hours per ticket
−12%
−0.11 h · range −14% to −11%
Quality guardrails
5 of 5 pass
Speed only counts if quality held
Cash ROI (P10 to P90)
7% to 79%
Counted · middle 40%
Capacity ROI (P10 to P90)
146% to 222%
2,590 agent hours released

AI agent assist (simulated) changed agent hours per ticket by -0.11 h per ticket (-12%; 95% range -0.13 to -0.09 h, -14% to -11%). Evidence grade B. Guardrails: all pass. Cash ROI 7% to 79% (P10 to P90).

Renew and expandCash ROI is positive even at the low end of the range.

2The question as registered

3Design

Staggered rollout (imputation difference-in-differences).

Evidence grade B: Comparison-group design with diagnostics passed: counts toward measured ROI.

4Effects

Headline and mix-adjusted results side by side, per ticket. Negative means less time. The mix-adjusted view compares tickets only with tickets of the same type.

MetricViewEffect95% rangeRelativeTotal over AI tickets
Agent hours per ticketheadline−0.03 h−0.05 to −0.01−3.3%−429 h
Agent hours per ticketmix-adjusted−0.11 h−0.13 to −0.09−12.2%−1,725 h
Resolution timeheadline+0.23 h−0.25 to +0.75+1.9%+3,651 h
Resolution timemix-adjusted−1.02 h−1.42 to −0.61−7.4%−16,001 h

Before and after, AI teams only

Descriptive: no comparison group, so not causal. It shows why the headline average can mislead.

MetricBefore AIAfter AIChange
Headline mean resolution time (h)12.612.7+1%
Mix-adjusted mean resolution time (h)12.611.6−8%
Agent hours for the same work14,281.912,460.5−13%

By work type

Work typeAI ticketsEffect (h)RangeRelative
Software / Application Error2,680−0.230−0.294 to −0.163−15%
Software / Installation2,394−0.075−0.105 to −0.039−10%
Hardware / Laptop2,190−0.126−0.219 to −0.043−9%
Account Access / Permissions2,027−0.056−0.085 to −0.032−11%
Software / Email1,840−0.051−0.082 to −0.021−8%
Account Access / Password Reset1,708−0.045−0.059 to −0.031−18%
Network / Connectivity1,465−0.117−0.201 to −0.040−10%
Inquiry / Help / General1,391−0.070−0.090 to −0.050−17%

AI was recorded on 77% of AI teams' tickets after rollout. Usage explains effects; it is never counted as value.

5Effect over time

Effect by week since rolloutWeekly effect estimates with 95% ranges. Weeks before rollout should hover around zero.-0.3-0.2-0.100.1rolloutWeek -8: +0.0332 hWeek -7: +0.00563 hWeek -6: -0.0393 hWeek -5: -0.0121 hWeek -4: +0.000605 hWeek -3: -0.0394 hWeek -2: +0.0119 hWeek -1: -0.0367 hWeek 0: -0.038 hWeek 1: -0.0495 hWeek 2: -0.0636 hWeek 3: -0.0828 hWeek 4: -0.0532 hWeek 5: -0.108 hWeek 6: -0.127 hWeek 7: -0.15 hWeek 8: -0.122 hWeek 9: -0.169 hWeek 10: -0.166 hWeek 11: -0.0958 hWeek 12: -0.131 hWeek 13: -0.0794 hWeek 14: -0.17 hWeek 15: -0.0905 hWeek 16: -0.0589 hWeek 17: -0.113 hWeek 18: -0.145 hWeek 19: -0.139 hWeek 20: -0.0299 hWeek 21: -0.105 hWeek 22: -0.176 hWeek 23: -0.126 hWeek 24: -0.115 hWeek 25: -0.123 hWeek 26: -0.146 hWeek 27: -0.0557 hWeek 28: -0.0889 hWeek 29: -0.103 hWeek 30: -0.227 hWeek 31: -0.136 hWeek 32: -0.221 hWeek 33: -0.164 h-8-4048121620242832Weeks since rolloutEffect (h)
Mix-adjusted agent hours per ticket by week since rollout, with 95% ranges. Grey points before rollout should sit near zero; the green line shows the learning curve after it.

6Quality guardrails

GuardrailAllowedStatusDetail
Reopen raterise of at most 0.01 (share)PassChange +0.00188 (share) (range -0.00261 to +0.00664); within the limit.
Reassignments per ticketrise of at most 0.1PassChange -0.00464 (range -0.0246 to +0.0162); within the limit.
Escalation raterise of at most 0.01 (share)PassChange -0.00104 (share) (range -0.00887 to +0.00589); within the limit.
Satisfaction scorefall of at most 0.1 ptsPassChange +0.000737 pts (range -0.0451 to +0.0528); within the limit.
False deflection rateat most 15%Pass13.6% of resolved sessions came back as a ticket within 7 days (range 12.5% to 14.8%).

7Diagnostics

CheckResultDetail
Pre-trend testPassAI and comparison teams moved together before rollout (joint p = 0.38 over 8 weeks).
Placebo datesPassA fake rollout 8 weeks early shows no effect (-0.0109, range -0.0386 to +0.0147).
Placebo outcome: Share of tickets opened outside business hoursPassA metric the AI cannot affect did not move (+0.0057).
Leave-one-team-outPassDropping any one AI team keeps the estimate between -0.112 and -0.106.
Category driftPassNo sign that the category taxonomy changed with the rollout.
PowerPassWith this data the smallest reliably detectable effect is ±0.0218 per unit of work (±2%).

8Value and ROI

Period: 7.8 months from first rollout. Ranges from 10,000 simulations combining the measured effect's uncertainty with the assumptions in section 10.

Low (P10)Middle (P50)High (P90)
Agent hours released2,3432,5902,849
Capacity value$138,059$156,639$177,415
Cash value$59,413$78,103$98,716
Total cost$52,955$55,588$58,306
Capacity ROI146%182%222%
Cash ROI7%40%79%
Cost per agent hour released$19$21$24

Payback, middle case: 3.3 months on a cash basis; 1.1 months on a capacity basis.

Verified deflection

3,543 self-service resolutions: 3,061 verified, 482 false (13.6% came back within 7 days). 1,150 agent hours avoided. Counted: verified resolutions and a measurable fall in ticket volume for AI teams.

Costs for the period

ComponentDescriptionBasisLowMost likelyHigh
licenseAI add-on licence uplift (illustrative)annual$31,146$31,146$31,146
build_integrationImplementation partner (illustrative)one_time$8,000$10,000$14,000
change_trainingAgent training: 300 agents × 20 min × $60one_time$6,000$6,000$6,000
human_oversightKnowledge-base upkeep and AI review timemonthly$3,893$7,786$11,680

9Claimed versus proven

SourceClaimed hoursClaimed valueMeasured hours (P10 to P90)Note
Vendor value dashboard (illustrative)9,000n/a2,343 to 2,849Usage × assumed minutes saved per summary

Claimed figures are grade E: shown for comparison, never added to measured value.

10Assumptions

AssumptionLowMost likelyHighUnitOwnerAgreed
Loaded cost per agent hour52.0060.0070.00USDFinance partner, IT (illustrative)2025-11-10
Share of freed hours provably redeployed (realization)0.300.500.70shareFinance partner, IT (illustrative)2025-11-10
Extra agent hours per false deflection0.250.501.00hFinance partner, IT (illustrative)2025-11-10

11Data lineage

FileRowsModifiedSHA-256
incidents.csv74,4772026-10-17T05:00:27+00:00a5dd9e825b4798c2…
rollout.csv402026-10-17T05:00:27+00:00dca626de90094161…
virtual_agent.csv4,7412026-10-17T05:00:27+00:0045589c60796fe765…

Probative Labs 0.4.0 (git 699d0675540a) · configuration 383f5b08a739 · run 2026-10-17T05:00:28+00:00

12Recommendation

Renew and expand. Cash ROI is positive even at the low end of the range.

A rule-based suggestion from the evidence above. The decision belongs to the program owner and finance.

Method appendix

Estimator

Effects are estimated with the imputation estimator for staggered adoption (Borusyak, Jaravel and Spiess, Review of Economic Studies, 2024). Team and week effects are fitted by weighted least squares using only team-weeks without the AI (comparison teams, and AI teams before their rollout). For every team-week with the AI, the fitted model predicts the outcome it would have had without it; the effect is the observed minus the predicted outcome. Effects are averaged with weights equal to the number of tickets in each team-week, so the headline is an effect per ticket.

Because AI team-weeks are only ever compared with untreated data, the estimator avoids the bias of ordinary two-way fixed-effects regressions under staggered rollouts with effects that change over time. A single rollout date with a comparison group reduces to two-group difference-in-differences.

Uncertainty

Ranges come from a bootstrap that resamples whole teams (499 draws, seed 20261014), stratified by rollout wave so every draw keeps the design. Intervals are percentile intervals at the 95% level. Tickets within a team are not independent, so resampling teams, not tickets, gives honest uncertainty.

Work typing and mix adjustment

Each ticket is typed from its category fields (and any custom rules). Types below the configured share of baseline volume are folded into 'Other'. Mix-adjusted outcomes subtract each type's baseline mean (computed on untreated team-weeks only) before averaging, so the engine compares tickets only with tickets of the same type. The headline (unadjusted) estimate is always reported beside it.

The descriptive before/after table reweights each period's per-type means to the AI teams' before-rollout mix; it has no comparison group and is not causal.

Diagnostics

Quality guardrails

Each guardrail is estimated with the same design (type-adjusted). Pass: the upper end of the harm range is below the threshold. Breach: the harm exceeds the threshold and its range excludes zero. Watch: otherwise. Any breach withholds the program's value. The false deflection rate is judged on its level (Wilson interval) against its threshold.

Value and ROI

Capacity value = (agent hours saved + verified deflections × baseline hours for that type − false deflections × extra hours) × loaded hourly cost. Cash value = capacity value × realization share + documented realized savings. ROI = (value − total cost) ÷ total cost.

Hours saved enter through their team-bootstrap draws; each customer assumption enters as a triangular distribution (low, most likely, high). The simulation reports the 10th, 50th and 90th percentiles. Payback = one-time costs ÷ (monthly value − monthly recurring cost).

Deflection counts only when the evidence grade counts, no guardrail breached, and ticket volume per team fell measurably for AI teams.

Evidence grades

Data handling

Reproduce this result

Run `probative analyze -c probative.yaml` with the same data files, configuration and pseudonymization key. Results are deterministic given the seed.