Add study_013: Keh, Foo & Lim (2002) — Opportunity Evaluation under Risky Conditions

New study contribution examining how cognitive biases (overconfidence, illusion of control,
planning fallacy, belief in small numbers) affect entrepreneurs' opportunity evaluation,
mediated by risk perception. Based on survey data from 77 Singaporean SME founders.

Includes:
- Full questionnaire (Sections A-D) with verbatim stimuli from paper appendix
- 10 overconfidence items with answers verified against Singapore Yearbook of Statistics 2000
- 5 findings (F1-F5): overconfidence t-test + 4 Pearson correlations
- config.py with persona-varied prompt generation (40 questions per trial)
- evaluator.py with one-sample t-test and correlation-based replication testing

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: zgk2003

studies/study_013/README.md

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+# Study 013: Opportunity Evaluation under Risky Conditions
+
+**Authors:** Hean Tat Keh, Maw Der Foo, Boon Chong Lim
+
+**Year:** 2002
+
+**Journal:** *Entrepreneurship Theory and Practice*, 27(2), 125-148
+
+## Description
+
+This study examines how cognitive biases affect entrepreneurs' opportunity evaluation under risky conditions. Using a survey of 77 founders of top SMEs in Singapore, the study measures four cognitive biases (overconfidence, illusion of control, belief in the law of small numbers, and planning fallacy) and tests how they influence risk perception and opportunity evaluation of a standardized business case vignette.
+
+## Participants
+
+- **N = 77** founders and owners of the top 500 SMEs in Singapore
+- 97% male, mean age 46.6 years
+- 92.4% Chinese, 79% founded their business
+- Business revenue: 48.6% between S$1M-S$25M, 44.4% between S$25M-S$50M
+
+## Key Findings Tested
+
+| Finding | Hypothesis | Human Result |
+|---------|-----------|--------------|
+| F1 | Entrepreneurs are overconfident (mean items outside 90% CI > 1) | Mean = 5.17, SD = 2.64 |
+| F2 | Risk perception negatively associated with opportunity evaluation | r = -.58, p < .01 |
+| F3 | Illusion of control negatively associated with risk perception | r = -.44, p < .01 |
+| F4 | Illusion of control positively associated with opportunity evaluation | r = .34, p < .01 |
+| F5 | Overconfidence positively associated with opportunity evaluation | r = .30, p < .05 |
+
+## Questionnaire Structure
+
+- **Section A:** 5 forced-choice gamble items (risk propensity)
+- **Section B:** 7 Likert items (2 filler, 2 planning fallacy, 3 illusion of control)
+- **Section C:** 10 confidence-interval estimation items (overconfidence)
+- **Section D:** Business case vignette + 4 risk perception items + 3 opportunity evaluation items + 1 open-ended item
+
+## File Structure
+
+```
+study_013/
+├── index.json
+├── README.md
+├── source/
+│   ├── Keh-Foo-Lim-2002-Opportunity-Evaluation.pdf
+│   ├── metadata.json
+│   ├── specification.json
+│   ├── ground_truth.json
+│   └── materials/
+│       ├── section_a_risk_propensity.json
+│       ├── section_b_cognitive_biases.json
+│       ├── section_c_overconfidence.json
+│       └── section_d_case_vignette.json
+└── scripts/
+    ├── config.py
+    ├── evaluator.py
+    ├── study_utils.py
+    └── stats_lib.py
+```
+
+## Overconfidence Answer Key
+
+The 10 confidence-interval items reference Singapore statistics circa 1999-2000. Correct answers have been verified against:
+- Yearbook of Statistics Singapore 2000 (Department of Statistics)
+- Changi Airport Group corporate history
+- LTA Vehicle Quota Tender Results 2000-2004
+- SingStat residential dwelling datasets
+
+## Contributor
+
+Guankai Zhai ([@zgk2003](https://github.com/zgk2003))

studies/study_013/index.json

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+{
+  "title": "Opportunity Evaluation under Risky Conditions: The Cognitive Processes of Entrepreneurs",
+  "authors": [
+    "Hean Tat Keh",
+    "Maw Der Foo",
+    "Boon Chong Lim"
+  ],
+  "year": 2002,
+  "description": "This study examines how cognitive biases affect entrepreneurs' opportunity evaluation under risky conditions. Using a survey of 77 founders of top SMEs in Singapore, the study measures overconfidence, illusion of control, belief in the law of small numbers, and planning fallacy, and tests how these biases influence risk perception and opportunity evaluation of a standardized business vignette. Results show that illusion of control reduces risk perception, which in turn increases opportunity evaluation (full mediation), while belief in the law of small numbers directly increases opportunity evaluation. Entrepreneurs are found to be significantly overconfident in their knowledge calibration.",
+  "contributors": [
+    {
+      "name": "Guankai Zhai",
+      "github": "https://github.com/zgk2003"
+    }
+  ]
+}