🎂 Birthday Paradox · Sports
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Olympic Swimming (Aquatics)

Delegation

682 team lists · 9,984 player entries · avg team size 14.6

Read this sport as a comparison between raw coincidence and what team size alone predicts. Here, the real rate is -0.1 points below the birthday-paradox baseline.

Real team lists
25.8%
teams with shared birthdays
Why it matters: This is the headline rate, but it should never be read without team size.
Expected from size
25.9%
from avg team size
Why it matters: This is the fair baseline: what same-size random teams would do.
Gap from expected
-0.1 points
real − expected
Why it matters: Negative means this sport is quieter than team size alone predicts.
Team lists
682
teams analysed
Why it matters: Enough team lists for a useful sport-level read.
What to notice: The best question on a sport page is not "is the real rate high?" but "is it high after accounting for team size?" That is what the gap card is answering.

Country comparison

Countries with the most team lists for Olympic Swimming (Aquatics), charted by the share of teams with at least one shared birthday.

What to compare: This view is best for spotting sample-shape differences inside a sport. Among the highest-sample countries, USA has the highest observed rate, with an average team size of 35.7.

Gender split inside this sport

Real and expected rates for labelled team lists in this sport.

Why it matters: The gender gap is mostly a team-size story. Women have the larger average team size here (15.6 athletes), so their birthday-match rate naturally rises.

By country

Top 40 countries by team-list count.

CountryTeam listsAvg playersReal
FRA2717.014.8%
GBR2726.633.3%
USA2635.773.1%
HUN2515.948.0%
SWE2514.428.0%
AUS2424.254.2%
NED2214.927.3%
JPN2122.242.9%
CAN2121.528.6%
ITA2019.650.0%
BRA1813.927.8%
ESP1813.411.1%
BEL177.75.9%
GER1623.950.0%
DEN159.46.7%
MEX1410.914.3%
AUT137.730.8%
POL1310.27.7%
NZL139.615.4%
SUI128.68.3%
ARG128.316.7%
FIN127.816.7%
RSA1111.09.1%
POR108.020.0%
CHN1026.970.0%
URS923.866.7%
PHI85.90.0%
ROU88.00.0%
KOR815.112.5%
GRE813.437.5%
UKR715.714.3%
HKG78.00.0%
SGP75.40.0%
SLO77.914.3%
RUS727.457.1%
BLR78.00.0%
CZE78.128.6%
ISR67.30.0%
VEN68.50.0%
ISL67.50.0%
What to notice: Countries with larger average teams will naturally show more shared birthdays. The country list is most useful for finding which samples are driving this sport's overall rate.

By gender

Where the dataset records it.

GenderTeam listsRealExpectedGap
Women49329.4%28.3%+1.1 points
Men18916.4%19.8%-3.4 points

Sample team lists

Largest teams in the dataset.

TeamSeasonPlayersRepeatsExpected chance
USA Swimming (Aquatics) (1968 Summer) · USA1968 Summer52297.8%
USA Swimming (Aquatics) (1972 Summer) · USA1972 Summer51197.4%
USA Swimming (Aquatics) (1976 Summer) · USA1976 Summer51497.4%
USA Swimming (Aquatics) (2000 Summer) · USA2000 Summer48196.1%
USA Swimming (Aquatics) (1964 Summer) · USA1964 Summer48396.1%
USA Swimming (Aquatics) (2020 Summer) · USA2020 Summer48396.1%
USA Swimming (Aquatics) (2012 Summer) · USA2012 Summer47295.5%
USA Swimming (Aquatics) (2016 Summer) · USA2016 Summer45294.1%
FRG Swimming (Aquatics) (1972 Summer) · FRG1972 Summer44193.3%
USA Swimming (Aquatics) (1988 Summer) · USA1988 Summer44393.3%
What to notice: The sample team lists show the mechanics: once the player count gets large, the expected chance climbs quickly, and each repeat is another player landing on a date already present.