J. Jeffrey Inman

J. Jeffrey Inman

Marketing researcher whose in-store studies measured how often shoppers buy what they did not plan to.

Who they are

The 2004 working-paper version of his best-known study lists Inman at the Katz Graduate School of Management, University of Pittsburgh. With Russell Winer and Rosellina Ferraro, he interviewed 2,300 shoppers in 28 stores for a 2009 paper in the Journal of Marketing. The baseline chance of an unplanned purchase was 46 per cent, rising to 93 per cent when contextual factors stacked up. Using a list, making more frequent trips, visiting fewer aisles, spending less time in store and paying by cash were linked to fewer unplanned purchases.

With Karen Stilley and Kirk Wakefield, he reported in 2010 that shoppers hold mental trip budgets that include unassigned in-store slack, kept for decisions made at the shelf.

Key papers

Inman, J. J., Winer, R. S., & Ferraro, R. (2009). "The interplay among category characteristics, customer characteristics, and customer activities on in-store decision making." Journal of Marketing, 73(5), 19-29. doi:10.1509/jmkg.73.5.19.

Stilley, K. M., Inman, J. J., & Wakefield, K. L. (2010). "Planning to make unplanned purchases? The role of in-store slack in budget deviation." Journal of Consumer Research, 37(2), 264-278. doi:10.1086/651567.

Key ideas

See Impulse Buying and In-Store Slack.

Sources

  1. Inman, Winer and Ferraro (2009), abstract read, and the 2004 working-paper version read in full, 13 October 2026.
  2. Stilley, Inman and Wakefield (2010), abstract read, 13 October 2026.