SOURCES

Filings and company results (chapters 4, 5, 10)

• Casper Sleep Inc. Form S-1 registration statement, January 2020.
• Casper Sleep Inc. Fourth quarter and full year 2019 results, March 19, 2020.
• Casper Sleep Inc. Pricing of initial public offering, February 5, 2020; CNBC on the range cut and first day of trading.
• Casper Sleep Inc. To be acquired by Durational Capital Management, November 15, 2021; completion, January 2022. Retail Dive on the sale to Carpenter Co.
• Allbirds, Inc. Form S-1 registration statement, 2021; IPO pricing, November 2, 2021; Crunchbase on first-day trading; full-year results for 2021 to 2024, including fourth quarter and full year 2024 results.
• Allbirds, Inc. Definitive asset purchase agreement with American Exchange Group, March 30, 2026; Retail Dive on the renaming. The 1-for-20 reverse stock split was announced in a Form 8-K, August 2024.
• Allbirds, Inc. Fourth quarter 2022 earnings call transcript, March 9, 2023.
• Warby Parker Inc. Form S-1 registration statement, 2021; full year 2024 results; full year 2025 results; CNBC on the direct listing, September 29, 2021.

Advertising and measurement (chapters 6, 7, 8)

• Thomas Blake, Chris Nosko and Steven Tadelis. “Consumer Heterogeneity and Paid Search Effectiveness: A Large-Scale Field Experiment.” Econometrica 83(1), 2015. Working paper.
• Brett R. Gordon, Florian Zettelmeyer, Neha Bhargava and Dan Chapsky. “A Comparison of Approaches to Advertising Measurement: Evidence from Big Field Experiments at Facebook.” Marketing Science 38(2), 2019.
• Randall A. Lewis and Justin M. Rao. “The Unfavorable Economics of Measuring the Returns to Advertising.” Quarterly Journal of Economics 130(4), 2015.
• Apple. iOS 14.5 release, April 26, 2021. Meta Platforms. Fourth quarter 2021 earnings call transcript, February 2, 2022.
• William N. McPhee. Formal Theories of Mass Behavior. Free Press, 1963.
• Andrew Ehrenberg, Gerald Goodhardt and Patrick Barwise. “Double Jeopardy Revisited.” Journal of Marketing 54(3), 1990. Byron Sharp, How Brands Grow, Oxford University Press, 2010. Ehrenberg-Bass Institute, on acquisition and retention (Riebe et al., Journal of Business Research, 2014).
• Les Binet and Peter Field. The Long and the Short of It, IPA, 2013; IPA on the updated findings.
• Eugene M. Schwartz. Breakthrough Advertising. Prentice-Hall, 1966.

Site and checkout (chapter 9)

• Baymard Institute. Cart abandonment rate statistics, 2025.
• Spiegel Research Center, Northwestern University. “How Online Reviews Influence Sales,” June 2017.
• Deloitte Digital for Google. “Milliseconds Make Millions,” 2020.
• Apple. Human Interface Guidelines: Buttons. W3C. Understanding Success Criterion 1.4.3: Contrast (Minimum).

Email and SMS (chapters 13 to 18)

• Google. Email sender guidelines and sender guidelines FAQ. Yahoo. Sender best practices.
• Apple. Privacy announcement, June 7, 2021; iOS 15 release, September 20, 2021; Mail Privacy Protection.
• Klaviyo. Email marketing benchmarks, 2026 (vendor data). Omnisend. 2026 ecommerce marketing report (vendor data).
• 47 CFR 64.1200, Delivery restrictions. Facebook, Inc. v. Duguid, 592 U.S. 395 (2021).
• Florida Statutes section 501.616, as amended by SB 1120 (2021).
• Twilio. US A2P 10DLC blocking of unregistered traffic. The Campaign Registry.
• Federal Trade Commission. Negative option rule; advance notice of proposed rulemaking, March 2026. Mayer Brown on the Eighth Circuit decision, July 2025.

Loyalty, testing and the offer (chapters 11, 19, 21)

• Joseph C. Nunes and Xavier Drèze. “The Endowed Progress Effect.” Journal of Consumer Research 32(4), 2006.
• Ran Kivetz, Oleg Urminsky and Yuhuang Zheng. “The Goal-Gradient Hypothesis Resurrected.” Journal of Marketing Research 43(1), 2006. The goal-gradient idea goes back to Clark L. Hull, “The Goal-Gradient Hypothesis and Maze Learning,” Psychological Review 39(1), 1932.
• Sheena S. Iyengar and Mark R. Lepper. “When Choice Is Demotivating.” Journal of Personality and Social Psychology 79(6), 2000. Benjamin Scheibehenne, Rainer Greifeneder and Peter M. Todd. “Can There Ever Be Too Many Options?” Journal of Consumer Research 37(3), 2010.
• Michael Lewis. “Customer Acquisition Promotions and Customer Asset Value.” Journal of Marketing Research 43(2), 2006. Eric T. Anderson and Duncan I. Simester. “Long-Run Effects of Promotion Depth on New Versus Established Customers.” Marketing Science 23(1), 2004.