The claim
For a model of intermittent demand with Bernoulli occurrence independent of a positive continuous size , the observed-data likelihood is in which the unobserved sizes do not appear and the size and occurrence parts separate.
Scope: population: models of intermittent demand (iETS, ADAM with an occurrence part); data: intermittent demand time series; conditions: Bernoulli occurrence independent of a continuous demand size · Proof: E1 · Assumes: C30, C31, C32 · Extends: B1 · Extends: B4, Appendix B, eq. B.6 · Verification: checked by an agent
Evidence
Assumptions
The errors of the single source of error model are independent across periods. Rested on by C1.
Definitions
Concepts 1
D3 observed-data likelihood: The joint density of the observed data only, obtained by integrating the complete-data likelihood over the values at the unobserved periods:
Context
- Extends B1 · from C1
- Dempster, Laird and Rubin define the EM algorithm, which maximises the likelihood of incomplete data through the expected complete-data log-likelihood.
- Extends B4, Appendix B, eq. B.6 · own earlier work · from C1
- Svetunkov and Boylan define iETS, intermittent demand as the product of a Bernoulli occurrence and a demand size modelled by exponential smoothing, and estimate it with a likelihood that adds the differential entropy of the size for each period with zero demand.
Artefacts
- A1 · manuscript LaTeX source of the draft 'Estimating exponential smoothing with unobserved periods: the observed-data likelihood of ADAM and iETS' (October 2026).
- A10 · proof Report of the first round of the independent proof check by the contributor P6 (2026-11-11): for C1, C2, C5, C6, C8, C10, C12, C14, C16 and C19, the re-derivation, the numerical spot checks, the outcome and the gaps found.
- A11 · proof Report of the second round of the independent proof check by P6 (2026-11-11), on C2, C5, C10, C14 and C19 as corrected after the first round, and on the smaller changes to C1, C6, C8 and C16.
- A14 · code Numerical spot checks of the first round of the proof check (Python with numpy); the report A10 says which claim each serves.
- A16 · code Numerical spot checks of the proof check (Python with numpy), used in both rounds; the reports A10 and A11 say which claim each serves.
Score
Scores are computed by rules from the claimset file (EntryLib rubric 0.2): they check the record, not the science, and may change as the rubric and reviews develop. The rubric.
C1: 95, High
Novelty: new, by the authors · no close match on EntryLib
- −3 Open problems Assumption C30 is not checked: The errors $\epsilon_t$ of the single source of error model are independent across periods. To remove it: Test the assumption, or analyse how sensitive the claim is to it.
- −1 Open problems Assumption C31 is not checked: In the intermittent demand model the occurrence $o_t$ is independent of the potential demand size $z_t$. To remove it: Test the assumption, or analyse how sensitive the claim is to it.
- −1 Open problems Assumption C32 is not checked: The potential demand size $z_t$ has a continuous distribution, so that $P(z_t=0)=0$. To remove it: Test the assumption, or analyse how sensitive the claim is to it.