Evidence Ledger
Jason Hreha·
Updated January 31, 2026
Each global claim links here. Rows include domain, measurement, effect size, window, sources, and confidence level.
How to read a row
- Effect size always in percentage points for the target behavior, not proxies
- Window is explicit (for example D0-D7)
- Sources link to a case write-up and raw data when possible
| ID | Claim | Domain | Effect size | Window | Confidence | Sources |
|---|---|---|---|---|---|---|
| BS-0001 | Behavior-first validation during planning improves initiative success compared with assumption-first approaches. | Cross-industry | Qualitative pattern across the case library (no single published effect size) | Project-specific | Working | Case |
| BS-0002 | Shorter time to first target behavior correlates with higher medium-term retention. | Consumer and SaaS | Product- and cohort-specific (validate per segment; no single published effect size) | Baseline to 90 days (or product-specific) | Working | Method |
| BS-0003 | At-scale nudge-unit RCTs show small average effects (~1.4 pp), far below academic journal averages (~8.7 pp). | Public sector and enterprise | ~1.4 pp average (vs ~8.7 pp in academic journals) | 126 RCTs; 23 million individuals | High | Study |
| BS-0004 | Opt-out (default) organ donation regimes do not reliably increase transplantation; complementary system investments drive outcomes. | Healthcare policy | No reliable increase in deceased donation after opt-out policy shifts; some evidence of decreased living donation (−29%) | Cross-national, multi-year comparisons | High | Review, Study, Study |
| BS-0005 | Pivoting from low-fit behaviors to high-fit behaviors drives rapid adoption (Instagram: check-ins → photo sharing). | Technology | 25K users day 1; 100K in first week; 7M in 9 months (company-reported) | Launch window; first 60-90 days | Working | Interview, Podcast, Interview |
| BS-0006 | Behavior-first internal tool pivots (Slack) yield high early adoption and strong cohort retention when they solve real team behaviors. | Enterprise software | 8k users day-1; 93% team retention after 2+ weeks (company-reported) | First 30-90 days of public beta | Working | Interview |
| BS-0007 | Mobile money infrastructure (M-PESA) enables financial behaviors at population scale when environmental bottlenecks are removed. | Finance / Emerging markets | ~194,000 households (2%) lifted out of poverty in Kenya (study estimate); improved risk-sharing and consumption smoothing | Multi-year (Kenya; study periods vary) | High | Study, Study |
| BS-0008 | Personalized automation that removes choice overload (Spotify Discover Weekly) increases sustained discovery behaviors. | Technology / Media | 2.3 billion listening hours from 2015-2020; more than 100 billion tracks streamed through the feature and 56 million new artist discoveries per week by 2025 (company-reported) | 2015-2025 company milestones | Working | Company post, Company post, Company post |
| BS-0009 | Behavior scaffolding (micro-lessons, progress visibility, immediate feedback) enables durable learning behaviors (Duolingo). | Education / EdTech | Peer-reviewed evaluations report meaningful language learning gains for beginners using Duolingo over the study period | Study-specific (weeks to months) | Working | Study |
| BS-0010 | Frictionless access at scale (Zoom) drives massive increases in meeting participation when environmental constraints spike. | Enterprise / Communication | 10M → 300M daily participants (Dec 2019-Apr 2020); TTFB near-instant | Q1-Q2 2020 | Working | Company post |
| BS-0011 | Meta-analyses of choice architecture interventions show small-to-medium average effects with substantial heterogeneity and publication bias. | Cross-domain meta-analysis | d ≈ 0.43-0.45 (small-to-medium) | 214 publications; 455 effect sizes | High | Meta-analysis |
| BS-0012 | Commuter carpooling RCTs show context-bound effects; system design (safety, coordination, incentives) matters more than default prompts. | Transportation / Public policy | Varies; contingent on study design and system supports | Trial-specific | Working | RCT |
| BS-0013 | Home energy reports (Opower) generate small, persistent behavior changes; effects are modest and context-dependent. | Energy / Residential | Small average reductions; persistence with decay (10-20% decay/year after reports stop) | 12-24 months | High | RCT |
| BS-0014 | Eliminating transaction fees (Robinhood) removes economic friction and enables first-time investing behaviors for new segments. | Finance | Large platform growth; industry-wide fee elimination followed | 2013-2019 | Working | Industry |
| BS-0015 | Reputation and trust systems (Airbnb) enable high-stakes sharing behaviors; conversion improves when trust cues are salient. | Technology / Marketplaces | Conversion deltas vary by study; generally positive | 12-36 months | Working | Experiment |
| BS-0016 | Behavioral public strategy connects micro-foundations (individuals, teams, tools) to meso-level performance; simple nudges are brittle without system design. | Public policy | Not applicable; conceptual synthesis | Not applicable | High | Article |
| BS-0017 | Temporal design of measurement (windows, cadence) materially affects whether change is detected; precise temporal hypotheses improve detection. | Methods / Measurement | Not applicable; meta-analysis of temporal aspects | Not applicable | High | Meta-analysis, Review |
| BS-0018 | Self-identity explains additional variance in behavioral intentions beyond attitudes, subjective norms, and perceived behavioral control (TPB). | Psychology / Theory | r+ = 0.47; ΔR² ≈ 6% (intention) and 9% (identity) beyond TPB components | 40 independent tests; N = 11,607 | High | Meta-analysis |
| BS-0019 | Minimum-component (bottleneck) logic: the lowest-scoring determinant constrains behavior; addressing bottleneck components is necessary for reliable change. | Methods / Theory | Not applicable | Not applicable | High | Model |
| BS-0020 | Values-affirmation (identity-aligned) interventions yield durable academic benefits versus reminders alone. | Education | Context-dependent; durable effects reported in field studies | Multi-year | Working | Field |
| BS-0021 | Psychological targeting (personality-tailored messaging) outperforms generic messaging for persuasion and conversion. | Marketing / Persuasion | Positive treatment effects; varies by context | Campaign-specific | Working | Experiment |
| BS-0022 | In CB Insights’ startup post-mortem analysis, “no market need” is a top failure reason (#2). | |||||
| Product / Strategy | 35% (ranked #2; CB Insights) | Various; cross-company | High | Report | ||
| BS-0023 | The Fogg Behavior Model (B=MAP) established that behavior occurs when Motivation, Ability, and Prompt converge at the same moment. | Behavior Design / Theory | Defines Motivation, Ability, and Prompt as simultaneous conditions in the model; does not validate the later Behavior Fit Assessment | Since 2009 | High | Conference paper |
| BS-0024 | Reviews of value-based decision making and action control distinguish proposed Pavlovian, habitual, and goal-directed systems with different computational and neural properties. | Behavioral Neuroscience | Supports a qualified distinction among Pavlovian, habitual, and goal-directed control; does not imply that three simple systems universally govern every behavior | Established body of research | High | Review, Review |
| BS-0025 | Goal-directed behaviors are outcome-sensitive (change with reward devaluation); habits are not. Most meaningful behaviors are goal-directed, not habitual. | Behavioral Neuroscience | Robust dissociation across human and animal studies | Established body of research | High | Computational model, Review |
| BS-0026 | Habit formation research (66 days median) applies only to simple, automatic behaviors like drinking water, not to complex behaviors. | Habit Formation | Median 66 days (range 18-254) | 84-day study | High | Longitudinal study |
| BS-0027 | Bias-corrected analyses find an aggregated nudge effect (d = 0.270) that drops to near zero (d = 0.004) after publication-bias adjustment. | Nudge Effectiveness | d = 0.270 aggregate; d = 0.004 after publication-bias adjustment | 13 articles (14 meta-analyses); 1,638 primary studies; ~30M participants | High | Meta-analysis, Second-order meta-analysis |
| BS-0028 | Implementation intentions (if-then planning) improve goal achievement with medium-to-large effect size. | Behavior Planning | d = 0.65 (medium-large) | 94 studies, 8,000+ participants | High | Meta-analysis |
| BS-0029 | Intentions explain less than one-third of behavior variance; the intention-behavior gap is substantial and systematic. | Behavior Theory | TPB meta-analysis: ~27% of behavior variance explained; intention-change interventions shift intentions (d = 0.66) more than behavior (d = 0.36) | Meta-analyses across 185+ studies (TPB) and 47 experimental tests (intention → behavior) | High | Meta-analysis, Meta-analysis, Meta-analysis, Review |
| BS-0030 | Behavior is predicted by attitudes, subjective norms, and perceived behavioral control (Theory of Planned Behavior). | Behavior Theory | R² = 0.27-0.39 for intentions; varies for behavior | Foundational theory since 1991 | High | Theory paper |
| BS-0031 | Habits are triggered by context cues, not goals; stable contexts produce stable behaviors. | Habit Formation | Strong context effects for simple, repeated behaviors | Review synthesis | High | Review |
| BS-0032 | Automatic enrollment with escalation dramatically increases retirement savings behavior. | Finance / Behavior Design | Savings rates increased from 3.5% to 13.6% over 40 months | Multi-year longitudinal | High | Field study |
| BS-0033 | Self-control is a limited resource that depletes with use; environmental design sustains behavior better than willpower. | Self-Regulation | Significant depletion effects (though effect sizes debated in replications) | Meta-analytic synthesis | Working | Review |
| BS-0034 | General cognitive ability (GCA) predicts job performance with corrected validity around r=0.22 in 21st-century samples. | Cognitive Ability / Work | Observed r = 0.16; corrected r = 0.22 | 153 samples; N = 40,740 (21st-century) | High | Meta-analysis |
| BS-0035 | Academic performance is jointly predicted by cognitive ability and Big Five traits; cognitive ability accounts for most of the explained variance; conscientiousness is the largest trait contributor. | Education / Psychometrics | Combined explains 27.8% variance; cognitive ability 64% of explained variance; conscientiousness 28% | 267 samples; N = 413,074; 228 studies | High | Meta-analysis |
| BS-0036 | Big Five traits predict performance across criteria; conscientiousness shows the most consistent positive association; other trait effects vary by performance category. | Personality / Performance | Overall: conscientiousness ρ = 0.19; extraversion ρ = 0.10; agreeableness ρ = 0.10; neuroticism ρ = −0.12; openness ρ = 0.13. Category-specific: −0.13 to 0.24 | 54 meta-analyses; k = 2,028; N = 554,778 | High | Meta-analysis |
| BS-0037 | Big Five measures do not fully capture HEXACO scale variance; using Big Five instead of HEXACO entails a large loss of information. | Personality / Psychometrics | Large deficiency in capturing HEXACO variance (authors conclude loss comparable to discarding one Big Five scale) | Multiple Big Five measures compared with HEXACO-PI-R scales | High | Psychometrics |
| BS-0038 | Honesty-Humility is meaningful as a distinct factor; separating it from classic agreeableness-related facets improves prediction of deceit-related variables. | Personality / Psychometrics | Improved prediction reported for deceit-without-hostility variables after realignment | Lexical Big Five + Five-Factor Model facet realignment | High | Psychometrics |
| BS-0039 | Personality traits show high rank-order stability in adulthood; stability increases with age and reaches ~0.74 in later adulthood. | Personality / Psychometrics | r ≈ 0.74 (ages 50-70; ~6.7-year interval at peak) | 152 longitudinal studies; 3,217 test-retest coefficients | High | Meta-analysis |
| BS-0040 | Exercise/physical-activity identity correlates with physical activity behavior across studies. | Health Behavior / Physical Activity | r = 0.44 | Meta-analysis across 62 datasets | High | Meta-analysis |
| BS-0041 | In an exercise RCT, increases in exercise identity predict physical activity at follow-up beyond treatment condition. | Health Behavior / Maintenance | b = 16.76 minutes/week per +1 identity point (95% CI: 2.36-31.15) | 16-week RCT + follow-up; N = 130 | Medium | RCT |
| BS-0042 | Habit and identity are strongly correlated in health behaviors, consistent with a mutual reinforcement pathway for maintenance. | Health Behavior / Habit | r = 0.55 (95% CI: 0.49-0.60) | 19 articles; N = 13,340 | High | Meta-analysis |
| BS-0045 | Conscientiousness is consistently associated with healthier behavior patterns across health behavior domains. | Personality / Health Behavior | r ≈ 0.05 (physical activity) to r ≈ −0.28 (drug use), directionally consistent across domains | 194 studies | High | Meta-analysis |
| BS-0046 | Personality traits can change via intervention, but average effects are modest and typically require sustained effort. | Personality / Change | Average trait change d ≈ 0.37 across interventions | 207 intervention studies; 20,653 participants | High | Meta-analysis |
| BS-0047 | Personality-life outcome associations replicate at high rates in a preregistered, high-powered replication project (with expected direction and moderate effect-size shrinkage). | Personality / Replication | 87% of replications significant in expected direction; replication effect sizes averaged 77% of original effects | 78 replications across 4 samples; total N = 6,106 | High | Preregistered replication |
| BS-0048 | Traits can be modeled as density distributions of states: people show substantial within-person variability, yet their average trait levels (distribution means) are highly stable/reliable within experience-sampling windows. | Personality / Psychometrics | Location stability (Study 1, 2-week ESM): Extraversion 0.90, Agreeableness 0.94, Conscientiousness 0.87, Emotional Stability 0.90, Intellect 0.94 | Experience sampling over ~2 weeks; Study 1 N = 127 | High | Experience sampling |
| BS-0049 | Conscientiousness is associated with lower mortality risk across longitudinal cohorts. | Personality / Health | r = −0.11 (95% CI: −0.13 to −0.09) | Meta-analysis of 20 independent samples | High | Meta-analysis |
| BS-0050 | General mental ability is a strong predictor of performance in job training programs. | Cognitive Ability / Training | r ≈ 0.56 for job training performance | Meta-analytic synthesis (Schmidt & Hunter, 1998) | High | Meta-analysis |
| BS-0051 | A preregistered, 39-lab replication did not support the classic induced-compliance (high-choice > low-choice) attitude-change effect. | Social Psychology / Replication | Primary high-choice vs low-choice prediction not supported; counterattitudinal vs neutral contrast supported | 39 labs; 19 countries; N = 4,898 | High | Multilab preregistered replication |
| BS-0052 | A modern archival analysis concludes that key elements of the classic ‘When Prophecy Fails’ account were substantially inaccurate and involved serious ethical problems. | History / Research Integrity | Not applicable | Archival analysis published 2026 | Medium | Historical analysis |
| BS-0053 | A widely cited behavioral-ethics intervention paper on signature placement and honesty was retracted. | Behavioral Ethics / Retraction | Not applicable | Retraction published 2021 (original 2012) | High | Retraction |
| BS-0054 | Automatic enrollment dramatically increases 401(k) participation among new hires and anchors many participants to default contribution rates and asset allocations. | Finance / Defaults | Participation at 3-15 months tenure: 86% (automatic enrollment) vs 37% (opt-in). Default contribution adherence declines from 92% to 57% over 15 months. | 3-15 months of tenure; up to 15 months post-hire | High | Field study, Working paper |
| BS-0055 | Automatic enrollment can raise participation, but long-run retirement wealth effects can be modest after accounting for turnover and withdrawals. | Finance / Defaults | +0.6% of income in retirement savings; effects substantially smaller once accounting for job changes and cash-outs | Long-run model with turnover and withdrawals | Medium | Working paper |
| BS-0056 | Experimental attempts to induce habits in humans often fail; extensive training may not produce outcome-insensitive (habitual) responding. | Habit Formation / Neuroscience | Five experiments reported failures to induce habitual responding in humans | Five experiments | High | Journal article |
| BS-0057 | Acorns increases saving/investing contributions by piggybacking on an existing behavior (spending) via automatic round-ups. | FinTech / Personal finance | Average round-ups: ~$43 per customer per month (reported); >$150 invested in first 4 months from round-ups alone (company-reported) | Monthly; first 4 months post-enablement | Working | Company documentation, Company post, Press |
| BS-0058 | Active allocation behaviors (assigning dollars before spending) can be more durable than passive awareness tools for budgeting (YNAB vs Mint). | FinTech / Personal finance | Mint: 1.5M users at 2009 acquisition (reported) and later shutdown (2024). YNAB: sustained subscription model anchored in repeated allocation behavior. | 2007-2024 | Working | Company documentation, Press, Press |
| BS-0059 | ClassPass built a viable model around variety-seeking fitness behavior instead of forcing single-gym commitment. | Fitness / Marketplace | Reported partner-side pattern: high share of visits are to new studios early; usage concentrates after initial exploration (company/partner reporting varies). | 2012-2018 (model evolution) | Working | Press, Case write-up, Press |
| BS-0060 | Gym membership contracts often monetize overconfidence: people pay flat fees while under-attending and delaying cancellation. | Behavioral Economics / Fitness | Members overestimated visits (~9.5 forecast vs ~4.2 actual/month); flat-fee members attended ~4.3x/month and paid an effective price >$17/visit (field data). | 3 years; N=7,752 members (3 US health clubs) | High | Journal article |
| BS-0061 | Peloton grew by matching at-home exercise constraints with instructor-led classes and social reinforcement; adoption shifted as context shifted post-pandemic. | Fitness / Consumer subscription | Hardware-subscriber engagement spiked during COVID and normalized afterward (reported). | 2018-2023 | Working | Press, Press |
| BS-0062 | Social reinforcement (kudos) can modestly increase running frequency; Strava leverages social feedback and competition to sustain exercise behaviors. | Fitness / Social platforms | Receiving kudos is associated with increased running frequency (study of running clubs; magnitude context-specific); Strava reports 180M+ athletes in 185+ countries. | Study-specific (running clubs; longitudinal social network analysis) | Working | Journal article, Company |
| BS-0063 | Couch to 5K enables novice running by reducing capability barriers through progressive overload (walk/run intervals). | Fitness / Program design | Completion in one study: 27.3% (n=110); UK NHS Couch to 5K: millions of downloads and completions (reported). | 9-week program; app reporting (2016-2024) | Working | Study, Government |
| BS-0064 | Discord achieved adoption by formalizing an existing behavior chain (team voice + text coordination) for gaming groups and then expanding to broader communities. | Technology / Communication | 200M+ global monthly active users (company-reported, 2025); expansion beyond gaming (reported). | 2015-2025 | Working | Company, Reference |
| BS-0065 | Figma won by matching real collaborative design workflows: real-time multiplayer editing removed ‘handoff’ friction and enabled team co-creation behavior. | Technology / Work tools | Real-time multiplayer editing reduced coordination overhead by eliminating export/sync/email file behaviors (mechanism; quantitative varies). | 2016-2023 | Working | Company post, Press |
| BS-0066 | TikTok outcompeted Vine by reducing creator friction and increasing distribution predictability via algorithmic recommendations and longer-format flexibility. | Technology / Social media | Mechanism-level: recommendation feed makes reach less dependent on follower graphs; video-length flexibility expands viable content behaviors. | 2016-2024 | Working | Company post |
| BS-0067 | YouTube succeeded by pivoting from a low-fit behavior (video dating) to a higher-fit one (upload/share any video), then enabling creator incentives (Partner Program). | Technology / Creator platforms | At acquisition (reported): ~100M daily video views; ~65K new videos uploaded daily. | 2005-2007 | High | Filing, Press |
| BS-0068 | Netflix won by matching viewing behavior with subscriptions and eliminating late-fee friction; Blockbuster’s model depended on behavior (returns) people often failed to perform. | Media / Subscription | Netflix reported 857,000 subscribers at year-end 2002, 2.61 million at year-end 2004, and about 20 million at year-end 2010. Blockbuster projected that eliminating late fees would reduce 2005 operating income by $250 million to $300 million. | 1999-2010 | Working | Press, Press, Company filing, Company filing, Company filing, Company filing |
| BS-0069 | Google Wave failed because it required too much behavior change at once (new collaboration behaviors from everyone, unclear use case, high learning cost). | Technology / Collaboration tools | Creators reported misalignment between their needs and mass-market learning costs; early active usage was low relative to invites (reported). | 2009-2012 | Working | Interview, Reference |
| BS-0070 | Quibi failed because its core context assumption (commute ‘in-between moments’) collapsed at launch and the target behavior could not compete with free social video. | Media / Failures | Trial-to-paid conversion reported ~8% for early cohorts (Sensor Tower estimate); shutdown announced ~6 months post-launch. | Apr-Oct 2020 | Working | Press, Press, Press |
| BS-0071 | Meditation apps often suffer severe early attrition because the target behavior is effortful with delayed rewards; retention is typically low without strong fit and scaffolding. | Health / Digital therapeutics | Meta-analytic attrition ~25% (higher in larger studies); median 30-day retention for mindfulness apps reported ~4.7% (app analytics). | 30 days and longer; study-dependent | Working | Meta-analysis, Study |
| BS-0072 | Digital health apps lose many users early; onboarding and early time-to-first-benefit strongly shape whether behavior persists. | Health / Digital products | Health app dropout reported ~43%; median abandonment over time can exceed 70% (study-dependent). | First weeks to ~100 days (study-dependent) | Working | Study |
| BS-0073 | Simplifying HIV treatment behaviors (single-tablet regimens; long-acting injectables) improves adherence and clinical outcomes compared to higher-burden regimens. | Healthcare / Adherence | Meta-analysis: discontinuation 36.3% (single-tablet) vs 48.8% (multi-tablet); ~21% higher odds of undetectable viral load (reported). | Meta-analysis (study periods vary) | High | Meta-analysis, Meta-analysis, Report |
| BS-0074 | Meal kit subscriptions often churn because the target behavior (plan, cook, and manage deliveries weekly) has low fit for many households; effort and context constraints dominate. | Consumer subscription / Food | Blue Apron reported ~50% continuation after two weeks and ~10% after six months (press reporting; varies by cohort). | First 6 months | Working | Press, Press |
| BS-0075 | Waze scaled crowdsourced traffic reporting by making micro-contributions low-friction and rewarding, improving navigation outcomes. | Technology / Navigation | At acquisition: ~50M users (reported); incident reporting and map edits at large scale (reported). | 2009-2013 and beyond | Working | Press, Case write-up, Press |
| BS-0076 | Open-plan offices can backfire: face-to-face interaction drops sharply and digital messaging increases when noise and interruption costs rise. | Workplace design | Face-to-face interaction decreased ~70%; email increased ~56%; IM increased ~67% after open office adoption (field study). | Before/after move to open plan (Fortune 500 HQ) | High | Journal article, Review |
| BS-0077 | Responsible beverage service (RBS) training reduces over-service and alcohol-related harms by targeting the gatekeeper behavior that can change in the moment. | Public health / Alcohol harms | Oregon server-training mandate associated with a 23% reduction in fatal single-vehicle nighttime crashes; community reviews report reduced intoxicated driving and related harms. | 1986-1994 (Oregon); multi-study reviews | High | Systematic review, Study |
| BS-0078 | Reducing time-to-first-value in SaaS onboarding increases activation: Proposify improved onboarding by guiding users to the core workflow quickly. | SaaS / Sales enablement | Before redesign, only ~14% of trial users completed onboarding steps (company-reported). | Pre/post onboarding redesign (company-reported; dates vary) | Working | Company-reported, Company post |
How to add a row
- Add an entry to
/_data/evidence_ledger.yml. - Use
{% include evidence-ref.html id="BS-XXXX" %}next to the claim on the relevant page. - Keep denominators explicit and link to case write-ups.
How to read a row (example) #
| ID | Claim | Domain | Effect size | Window | Confidence | Sources |
|---|---|---|---|---|---|---|
| BS-0001 | TTFB < 5 min increased completion of account setup among new users | B2C mobile | Δ-B +14 pp (22→36) | D0-D7 post-exposure | Medium | Case write-up, Raw data |