Estimating Demand for Substitutable Products when Inventory Records are Unreliable

We present a procedure for estimating demand for substitutable products when the inventory record is unreliable and only validated infrequently and irregularly. The procedure uses a structural model of demand and inventory progression, which is estimated using a modified version of the Expectation M...

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Main Authors: Steeneck, Daniel, Eng-Larsson, Fredrik, Jauffred, Francisco
Format: Working Paper
Language:en_US
Published: 2016
Subjects:
Online Access:http://hdl.handle.net/1721.1/104928
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author Steeneck, Daniel
Eng-Larsson, Fredrik
Jauffred, Francisco
author_facet Steeneck, Daniel
Eng-Larsson, Fredrik
Jauffred, Francisco
author_sort Steeneck, Daniel
collection MIT
description We present a procedure for estimating demand for substitutable products when the inventory record is unreliable and only validated infrequently and irregularly. The procedure uses a structural model of demand and inventory progression, which is estimated using a modified version of the Expectation Maximization-method. The procedure leads to asymptotically unbiased estimates without any restrictive assumptions about substitution patterns or that inventory records are periodically known with certainty. The procedure converges quickly also for large product categories, which makes it suitable for implementation at retailers or manufacturers that need to run the analysis for hundreds of categories or stores at the same time. We use the procedure to highlight the importance of considering inventory reliability problems when estimating demand, first through simulation and then by applying the procedure to a data set from a major US retailer. The results show that for the product category in consideration, ignoring inventory reliability problems leads to demand estimates that on average underestimate demand by 5%. It also results in total lost sales estimates that account for only a fraction of actual lost sales.
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spelling mit-1721.1/1049282019-04-10T15:19:19Z Estimating Demand for Substitutable Products when Inventory Records are Unreliable Steeneck, Daniel Eng-Larsson, Fredrik Jauffred, Francisco demand estimation inventory uncertainty choice behavior multinomial logit model EM method We present a procedure for estimating demand for substitutable products when the inventory record is unreliable and only validated infrequently and irregularly. The procedure uses a structural model of demand and inventory progression, which is estimated using a modified version of the Expectation Maximization-method. The procedure leads to asymptotically unbiased estimates without any restrictive assumptions about substitution patterns or that inventory records are periodically known with certainty. The procedure converges quickly also for large product categories, which makes it suitable for implementation at retailers or manufacturers that need to run the analysis for hundreds of categories or stores at the same time. We use the procedure to highlight the importance of considering inventory reliability problems when estimating demand, first through simulation and then by applying the procedure to a data set from a major US retailer. The results show that for the product category in consideration, ignoring inventory reliability problems leads to demand estimates that on average underestimate demand by 5%. It also results in total lost sales estimates that account for only a fraction of actual lost sales. 2016-10-21T22:02:53Z 2016-10-21T22:02:53Z 2016-10-21 Working Paper http://hdl.handle.net/1721.1/104928 en_US SCALE Working Paper Series;16-06 Attribution 3.0 United States http://creativecommons.org/licenses/by/3.0/us/ application/pdf
spellingShingle demand estimation
inventory uncertainty
choice behavior
multinomial logit model
EM method
Steeneck, Daniel
Eng-Larsson, Fredrik
Jauffred, Francisco
Estimating Demand for Substitutable Products when Inventory Records are Unreliable
title Estimating Demand for Substitutable Products when Inventory Records are Unreliable
title_full Estimating Demand for Substitutable Products when Inventory Records are Unreliable
title_fullStr Estimating Demand for Substitutable Products when Inventory Records are Unreliable
title_full_unstemmed Estimating Demand for Substitutable Products when Inventory Records are Unreliable
title_short Estimating Demand for Substitutable Products when Inventory Records are Unreliable
title_sort estimating demand for substitutable products when inventory records are unreliable
topic demand estimation
inventory uncertainty
choice behavior
multinomial logit model
EM method
url http://hdl.handle.net/1721.1/104928
work_keys_str_mv AT steeneckdaniel estimatingdemandforsubstitutableproductswheninventoryrecordsareunreliable
AT englarssonfredrik estimatingdemandforsubstitutableproductswheninventoryrecordsareunreliable
AT jauffredfrancisco estimatingdemandforsubstitutableproductswheninventoryrecordsareunreliable