Lewis (2006)
Michael Lewis, "Customer Acquisition Promotions and Customer Asset Value," Journal of Marketing Research 43, no. 2 (2006): 195–203. doi:10.1509/jmkr.43.2.195
What it found
At a newspaper and an online grocer, deeper acquisition discounts produced customers who repurchased less and were worth less. From the abstract: "a 35% acquisition discount results in customers with about one-half the long-term value of non-promotionally acquired customers."
Why it matters
The deeper the discount you acquire customers with, the less they end up being worth.
Read the explainer
Villanueva, Yoo & Hanssens (2008)
Julian Villanueva, Shijin Yoo and Dominique M. Hanssens, "The Impact of Marketing-Induced versus Word-of-Mouth Customer Acquisition on Customer Equity Growth," Journal of Marketing Research 45, no. 1 (2008): 48–59. doi:10.1509/jmkr.45.1.48
What it found
At a web-hosting firm, "marketing-induced customers add more short-term value, but word-of-mouth customers add nearly twice as much long-term value."
Why it matters
The channel a cohort came in through predicts what it'll be worth.
Datta, Foubert & van Heerde (2015)
Hannes Datta, Bram Foubert and Harald J. van Heerde, "The Challenge of Retaining Customers Acquired with Free Trials," Journal of Marketing Research 52, no. 2 (2015): 217–234. doi:10.1509/jmr.12.0160
What it found
At a digital-TV provider, behavioral differences "cause the average customer lifetime value of free-trial customers to be 59% lower than that of regular customers." Free-trial customers do respond more to marketing and to usage.
Why it matters
Judge your free trial on whether it pays back in lifetime value. Sign-ups alone won't tell you.
Anderson & Simester (2004): the counterpoint
Eric T. Anderson and Duncan I. Simester, "Long-Run Effects of Promotion Depth on New versus Established Customers: Three Field Studies," Marketing Science 23, no. 1 (2004): 4–20. doi:10.1287/mksc.1030.0040
What it found
"Deeper price discounts in the current period increased future purchases by first-time customers … but reduced future purchases by established customers."
Why it matters
Discounts don't always bring in worse customers. It depends on who gets the discount.
Byers, Mitzenmacher & Zervas (2012)
John W. Byers, Michael Mitzenmacher and Georgios Zervas, "The Groupon Effect on Yelp Ratings: A Root Cause Analysis," Proceedings of the 13th ACM Conference on Electronic Commerce (EC '12) (2012): 248–265. doi:10.1145/2229012.2229034
What it found
Merchants' Yelp ratings fall after they run Groupon deals. Across "over 7 million Yelp reviews," the authors test explanations and propose that deal customers are "real, unbiased customers" compared with inflated baseline reviews.
Why it matters
Customers who come in through deals behave differently, and so do the signals they leave, like reviews.
Schmittlein, Morrison & Colombo (1987)
David C. Schmittlein, Donald G. Morrison and Richard Colombo, "Counting Your Customers: Who Are They and What Will They Do Next?" Management Science 33, no. 1 (1987): 1–24. doi:10.1287/mnsc.33.1.1
What it found
The Pareto/NBD model estimates "the probability that any particular customer is still active" from the number and timing of past purchases.
Why it matters
How do you count live customers when there's no contract? This model does it.
Fader, Hardie & Lee (2005)
Peter S. Fader, Bruce G. S. Hardie and Ka Lok Lee, "'Counting Your Customers' the Easy Way: An Alternative to the Pareto/NBD Model," Marketing Science 24, no. 2 (2005): 275–284. doi:10.1287/mksc.1040.0098
What it found
The BG/NBD model is "vastly easier to implement" (it fits in Excel) and gives "very similar results."
Why it matters
This gives you a practical forecast of repeat purchases and lifetime value.
Fader & Hardie (2007)
Peter S. Fader and Bruce G. S. Hardie, "How to Project Customer Retention," Journal of Interactive Marketing 21, no. 1 (2007): 76–90. doi:10.1002/dir.20074 · free copy
What it found
The shifted-beta-geometric model fits in a spreadsheet. In the paper's words, "the observed phenomenon of increasing retention rates is simply a sorting effect in a heterogeneous population."
Why it matters
A cohort's retention rises with age because the leavers leave first. Nobody got more loyal. So read churn by cohort instead of as one blended rate.
Read the explainer
Fader & Hardie (2010)
Peter S. Fader and Bruce G. S. Hardie, "Customer-Base Valuation in a Contractual Setting: The Perils of Ignoring Heterogeneity," Marketing Science 29, no. 1 (2010): 85–93. doi:10.1287/mksc.1080.0482
What it found
"at the cohort level, retention rates typically increase over time." Using a single retention rate "yields a downward-biased estimate" of the customer base's remaining value.
Why it matters
Value your subscription book with one blended churn rate and you'll get it wrong.
Vaupel, Manton & Stallard (1979)
James W. Vaupel, Kenneth G. Manton and Eric Stallard, "The Impact of Heterogeneity in Individual Frailty on the Dynamics of Mortality," Demography 16, no. 3 (1979): 439–454. doi:10.2307/2061224
What it found
Life tables that ignore differences in frailty "overestimate current life expectancy … while underestimating rates of individual aging." The frail die first, which changes what the survivors' averages seem to say.
Why it matters
Fader and Hardie took this from demography and applied it to customers.
Gupta, Lehmann & Stuart (2004)
Sunil Gupta, Donald R. Lehmann and Jennifer Ames Stuart, "Valuing Customers," Journal of Marketing Research 41, no. 1 (2004): 7–18. doi:10.1509/jmkr.41.1.7.25084
What it found
Across five public firms, "a 1% improvement in retention, margin, or acquisition cost improves firm value by 5%, 1%, and .1%, respectively."
Why it matters
Retention is the biggest lever you have on firm value. So the next question is whose retention.
Reichheld & Sasser (1990)
Frederick F. Reichheld and W. Earl Sasser Jr., "Zero Defections: Quality Comes to Services," Harvard Business Review 68, no. 5 (1990): 105–111. hbr.org
What it found
"Companies can boost profits by almost 100% by retaining just 5% more of their customers." The case examples are 85% more profit at a bank's branch system, 50% at an insurance brokerage and 30% at an auto-service chain.
Why it matters
It's the most-quoted retention claim in business. The figures are case examples from the article, so don't treat them as a general law.
Reinartz & Kumar (2002)
Werner Reinartz and V. Kumar, "The Mismanagement of Customer Loyalty," Harvard Business Review 80, no. 7 (2002): 86–94. hbr.org
What it found
Across four companies and more than 16,000 customers over four years, the link between loyalty and profit was "much weaker—and subtler" than its proponents claimed. At one of the four, a high-tech corporate service provider, about half the customers who had bought regularly for at least two years "barely generated a profit."
Why it matters
Tenure doesn't tell you value, so put your retention effort where the value is.
Venkatesan & Kumar (2004)
Rajkumar Venkatesan and V. Kumar, "A Customer Lifetime Value Framework for Customer Selection and Resource Allocation Strategy," Journal of Marketing 68, no. 4 (2004): 106–125. doi:10.1509/jmkg.68.4.106.42728
What it found
"Customers who are selected on the basis of their lifetime value provide higher profits in future periods than do customers selected on the basis of several other customer-based metrics."
Why it matters
Rank your accounts on expected future value instead of past spend or count.
Ascarza (2018)
Eva Ascarza, "Retention Futility: Targeting High-Risk Customers Might Be Ineffective," Journal of Marketing Research 55, no. 1 (2018): 80–98. doi:10.1509/jmr.16.0163
What it found
"customers identified as having the highest risk of churning are not necessarily the best targets." Targeting by sensitivity to the intervention was "significantly more effective."
Why it matters
Aim your retention effort at the customers it actually changes, weighted by value, instead of at the highest churn scores.
Read the explainer
Ascarza, Iyengar & Schleicher (2016)
Eva Ascarza, Raghuram Iyengar and Martin Schleicher, "The Perils of Proactive Churn Prevention Using Plan Recommendations: Evidence from a Field Experiment," Journal of Marketing Research 53, no. 1 (2016): 46–60. doi:10.1509/jmr.13.0483
What it found
"whereas only 6% of customers in the control condition churned during the three months following the intervention, 10% did so in the treatment group."
Why it matters
Reach out to save customers and you can wake up "sleeping dogs" who would have stayed anyway.
Lemmens & Gupta (2020)
Aurélie Lemmens and Sunil Gupta, "Managing Churn to Maximize Profits," Marketing Science 39, no. 5 (2020): 956–973. doi:10.1287/mksc.2020.1229
What it found
Rank customers by the campaign's incremental effect on churn and on future cash flows, net of cost. "Two field experiments affirm that our approach leads to significantly more profitable campaigns than competing models."
Why it matters
Save your valuable customers instead of just chasing the ones most likely to leave.
Radcliffe & Simpson (2007); Siegel (2013): uplift's four groups
Nicholas J. Radcliffe and Rob Simpson, "Identifying Who Can Be Saved and Who Will Be Driven Away by Retention Activity," Stochastic Solutions white paper (2007), PDF; Eric Siegel, Predictive Analytics (Wiley, 2013).
What it found
Four groups:
- Persuadables: "made more likely to stay by treatment."
- Sure Things and Lost Causes: stay or leave "whether treated or not."
- Sleeping Dogs: "tend to be driven away by treatment."
Why it matters
Only spend where the effort changes the outcome. That goes for your ads as much as your retention, since brand search reaches sure things.
Yang, Eckles, Dhillon & Aral (2024)
Jeremy Yang, Dean Eckles, Paramveer Dhillon and Sinan Aral, "Targeting for Long-Term Outcomes," Management Science 70, no. 6 (2024): 3841–3855. doi:10.1287/mnsc.2023.4881
What it found
Targeting Boston Globe discounts on a surrogate for long-term retention beat targeting on short-term proxies. "Over three years, our approach had a net-positive revenue impact in the range of $4–$5 million."
Why it matters
Validate your early signals against long-term value, then use them to decide who to target.