Here you’ll test your grasp of decay mechanics and lag structures used to model delayed media effects. Expect questions on half‑life, lambda, and practical implications.
Adstock transforms apply a ______ factor to past spend before adding it to current effect.
decay
step
growth
random
The decay factor mimics memory wear‑off where past impressions fade over time.
A half‑life of 2 weeks means ad impact declines by ______ every 14 days.
50 %
100 %
10 %
25 %
Half‑life definition: effect halves over the specified period.
The exponential adstock formula is **Sₜ = Xₜ + λ·Sₜ₋₁** where λ must be between ______.
1 and 2
0 and 1
‑1 and 0
>1
Lambda represents the retention rate of previous period’s stock; values outside 0‑1 are invalid.
Weibull adstock allows for ______ build‑up before decay.
random
instant
delayed peak
negative
The Weibull kernel can capture saturation that rises then falls, unlike simple exponential.
2025 MMM toolkits default λ initialisation to 0.5 to speed up ______ convergence.
SQL query
Bayesian sampler
CSV import
Excel solver
Good priors reduce iterations in Bayesian optimisation.
If channel half‑life is estimated as 0 days, the model essentially reverts to ______ transformation.
no adstock
carry‑over
square root
Weibull
Zero half‑life means past impressions add no incremental effect.
Seasonal TV typically shows ______ half‑lives than always‑on search.
shorter
same
unpredictable
longer
TV brand memory lingers, producing longer decay tails.
Lag functions are applied after adstock to shift media impact by ______ periods.
CTR
lead time (e.g., shipping)
Budget phasing
CPC
Lag accounts for purchase latency like consideration or logistics.
When adstock λ is near 1, cumulative spend can create multicollinearity with the ______ variable.
device
trend
rand
weather
High persistence makes adstock series correlate with underlying trend, complicating coefficient estimation.
Choice of adstock function should reflect channel reality; for burst campaigns analysts sometimes prefer ______ decay.
infinite
step or geometric
negative
Log‑normal
Burst flights deliver near‑instant awareness followed by quick fade, matching step‑then‑none decay.
Starter
Review the basics.
Solid
Nice work—refine the details.
Expert!
Exceptional command of the topic.
