Two-thirds of the average.
Pick a number between 0 and 100: can you land closest to two-thirds of everyone's average?
Original study
- Keynes, J. M. (1936). The general theory of employment, interest and money (Chapter 12: The state of long-term expectation). Macmillan. Source
- Nagel, R. (1995). Unraveling in guessing games: An experimental study. American Economic Review, 85(5), 1313–1326. Source
- Bosch-Domènech, A., Montalvo, J. G., Nagel, R., & Satorra, A. (2002). One, two, (three), infinity, …: Newspaper and lab beauty-contest experiments. American Economic Review, 92(5), 1687–1701. Source
- Camerer, C. F., Ho, T.-H., & Chong, J.-K. (2004). A cognitive hierarchy model of games. Quarterly Journal of Economics, 119(3), 861–898. Source
Our adaptation
An online adaptation of Nagel's (1995) repeated 'p-beauty contest' guessing game (p = 2/3). In four rounds a whole number from 0 to 100 is chosen; the target of each round is 2/3 of the mean of the answers given in that round by participants who played it before. After each round the crowd mean and the target are shown.
Differences from the original study
- Opponents are not simultaneous but previous visitors; the target is computed from a growing crowd.
- There is no monetary prize.
- People who know the game may choose smaller numbers.
Measured variables
The columns of the open data file. List fields are expanded into numbered columns (for example rt_60, est_3); JSON columns contain only numbers and fixed stimulus names.
| Column | Type | Description |
|---|---|---|
g_1 | number | Number chosen in the round (0–100); the number at the end of the column is the round (g_1 … g_4). (item 1) |
g_2 | number | Number chosen in the round (0–100); the number at the end of the column is the round (g_1 … g_4). (item 2) |
g_3 | number | Number chosen in the round (0–100); the number at the end of the column is the round (g_1 … g_4). (item 3) |
g_4 | number | Number chosen in the round (0–100); the number at the end of the column is the round (g_1 … g_4). (item 4) |
Columns present in every file (14)
row_id | string | Row code. Regenerated at random in every release; it does not identify a person and cannot be matched across releases or experiments. |
experiment | string | Short name of the experiment (URL slug). |
experiment_version | integer | Version of the answer format. For experiments whose format changed, only the current format is published. |
date | YYYY-MM-DD | YYYY-Www | YYYY-MM | Day the answer was given (Istanbul time). If fewer than 5 answers share the same day, language and device, it is coarsened to the ISO week, and to the month if that is still too few. |
date_precision | day | week | month | Precision of the date column. |
lang | tr | en | (boş) | Interface language. Language recording started in the first week of October 2026; for earlier answers it is known only in experiments whose stimuli depend on the language, and empty otherwise. |
device | desktop | mobile | tablet | (boş) | Device class reported by the browser (class only; browser details are neither stored here nor published). |
source | site | embed | Where the answer came from: the balabs site or the experiment embedded on another site. The embedding site is not published. |
mode | free | daily | challenge | race | session | (boş) | Play mode in scored experiments: free play, daily round, challenge, race room, experiment session. Empty for unscored experiments and for older answers that did not store it. |
color_vision | normal | rg | by | contrast | (boş) | In color-based experiments, the color vision mode the participant chose: normal, red-green, blue-yellow or high contrast. Stimuli are generated along different axes per mode, so compare within a mode. Empty for other experiments. |
first_play | 1 | Every row is a participant’s first play of this experiment (always 1). Replays are stored only as leaderboard scores and are not part of the open data. |
seen_before | yes | no | unsure | (boş) | Participant’s own report of whether they had seen this experiment or its known answer before (in experiments that ask). |
duration_s | number | Time from the start of the experiment to submitting the answer, in seconds (measured in the browser, 0.1 s). |
play_score | number | Leaderboard score of the first play (scored experiments; defined on the method card). Empty for unscored experiments. |
Exclusion criteria
The server checks that each answer is a whole number from 0 to 100; invalid submissions are rejected. For participants who did not play all four rounds, later round columns are empty.
- Only each participant's first answer to this experiment; replays are not included.
- Simulated rows, bots, banned and sample accounts are not included.
- Answers before 3 October 2026 are not included (the first day the open data notice was live).
Scoring
Leaderboard score: the mean distance from target over four rounds; the target of each round is 2/3 of that round's crowd mean (a literature-based starting value while data are scarce). Lower is better. Because the target moves with the crowd, the score of the same answer can change over time; play_score is the value at the time of answering.
Leaderboard measure: distance from target (lower is better). The play_score column in the open data is this score for the first play.
Version notes
- October 2026
This experiment started storing the play mode (free, daily, challenge, race, session) with the answer; the mode column is empty for earlier answers.
- October 2026
The interface language (lang) started being stored with each answer; for earlier answers it is known only in experiments whose stimuli depend on the language, and empty otherwise.