Playbooks · TV budgeting
Blend TRPs across spot lengths and dayparts
This job produces one blended wTRP figure that converts a mixed 15s/30s, multi-daypart schedule into a single 30"-equivalent weight number. That figure feeds the buy approval decision and any cost-per-point negotiation with the sales house.
What you need first
- Schedule grid showing raw TRPs by spot length and daypart, pulled from the booking system or media plan
- Spot Length Coefficient table for the market (e.g. 30"=1.00, 20"=0.80, 15"=0.65, 10"=0.40), from the agency's standard conventions or the channel's own equivalency study
- Daypart definitions matching how the channel books and reports TRPs, from the channel's daypart grid
- Campaign TRP target or benchmark wTRP figure to check the blended result against, from the media plan objective
The procedure
- List every spot length by daypart combination with its raw TRP total, producing a grid of raw TRPs
- Apply the Spot Length Coefficient to each grid cell, producing a wTRP value per cell in 30"-equivalent units
- Sum the wTRP cells within each daypart, producing a daypart-level wTRP subtotal
- Sum the daypart subtotals into one figure, producing the blended wTRP for the whole schedule
- Divide blended wTRP by total raw TRP, producing the blended coefficient as a sanity check on the mix
- Compare blended wTRP against the campaign target or benchmark, producing the signal to approve or renegotiate the buy
Worked through with numbers
Prime time carries 120 raw TRP on 30s and 80 raw TRP on 15s; daytime carries 60 raw TRP on 30s and 40 raw TRP on 15s. Coefficients: 30s=1.00, 15s=0.65. Prime wTRP: 120×1.00=120 plus 80×0.65=52, subtotal 172 against 200 raw. Daytime wTRP: 60×1.00=60 plus 40×0.65=26, subtotal 86 against 100 raw. Blended wTRP total: 172+86=258. Total raw TRP: 200+100=300. Blended coefficient: 258/300=0.86. Read it as: the schedule nominally books 300 TRP but delivers the weight of 258 TRP once spot length is normalized to 30s, so any comparison to a 30"-based target or competitor buy uses 258, not 300.
Where it goes wrong
- Apply the coefficient at the cell level before summing, not to an already-averaged raw TRP figure, or short spots get overcounted
- Confirm the 15s coefficient with the current market or channel study instead of defaulting to 0.5, since most European recall studies put 15s closer to 0.6-0.7
- Check whether the channel revised its coefficient table this year before reusing last year's numbers, since equivalency studies get updated
- Convert any benchmark or competitor figure to the same 30"-equivalent base before comparing, since a raw TRP benchmark and a blended wTRP are not the same unit
How to know it is right
Recompute the blended coefficient (blended wTRP divided by raw TRP) and confirm it lands between the lowest and highest cell coefficient used, since a result outside that range means a summing or multiplication error.
Terms used