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Who actually improves the most between high school and college

The summer transition

For every sailor the model can track across both leagues, how does their rating change between their last high school regatta and their first college one — and does it depend on where they came from, or where they land?

How this is built: starts from the 3,490 sailors linked across ISSA and ICSA (see the recruiting guide), filtered to clean one-summer transitions — a last high-school race in spring, a first college race the following fall, 60–200 days apart (excludes gap years and mid-year transfers). Era boundaries are read directly from real race dates, not from the weekly-ratings file's own league label — that label turned out to only store one league per sailor and silently mislabels a bridged sailor's high-school-era weeks, a real data quirk this analysis has to work around rather than trust at face value. Rating "before" is the nearest fit at or before their last high school race; "after" is the nearest fit at or after their first college race.
896
Clean transitions found
+0.003
Overall mean rating change

Biggest jump, with a real sample size

Restricted to schools with more than 10 tracked sailors, so a single outlier can't drive the number — checked against both the strict clean-summer set above and the full unfiltered set (every linked sailor, including gap years and mid-year transfers) since they can tell different stories.

Clean summer only (n=896 total)
College (ICSA)College of Charleston+0.057 (n=15)
High school (ISSA)St. Thomas Aquinas High School+0.062 (n=11)
All transitions (n=2054 total)
College (ICSA)University of California at Santa Barbara+0.306 (n=32)
High school (ISSA)Lake Forest High School+0.255 (n=13)

Where sailors actually go

All 3,490 linked ISSA–ICSA sailors (not just the 896 clean-summer subset above) — ribbon width is the number of sailors making that conference-to-conference move. Regional pull is strong: sailors mostly stay in-region, but the exceptions are visible too.

Unknown → NEISA: 197 sailors Unknown → MAISA: 161 sailors Unknown → SAISA: 141 sailors Unknown → PCCSC: 87 sailors Unknown → MCSA: 69 sailors Unknown → NWICSA: 37 sailors Unknown → SEISA: 17 sailors Unknown → Unknown: 14 sailors NESSA → NEISA: 402 sailors NESSA → MAISA: 161 sailors NESSA → SAISA: 73 sailors NESSA → MCSA: 33 sailors NESSA → PCCSC: 29 sailors NESSA → SEISA: 12 sailors NESSA → Unknown: 6 sailors NESSA → NWICSA: 1 sailors MASSA → MAISA: 244 sailors MASSA → NEISA: 135 sailors MASSA → SAISA: 84 sailors MASSA → PCCSC: 21 sailors MASSA → MCSA: 18 sailors MASSA → SEISA: 8 sailors MASSA → Unknown: 2 sailors MASSA → NWICSA: 1 sailors MISSA → MCSA: 203 sailors MISSA → NEISA: 101 sailors MISSA → MAISA: 80 sailors MISSA → SAISA: 49 sailors MISSA → PCCSC: 26 sailors MISSA → NWICSA: 11 sailors MISSA → Unknown: 10 sailors MISSA → SEISA: 10 sailors PCISA → PCCSC: 207 sailors PCISA → NEISA: 133 sailors PCISA → MAISA: 73 sailors PCISA → SAISA: 30 sailors PCISA → NWICSA: 18 sailors PCISA → SEISA: 15 sailors PCISA → MCSA: 10 sailors PCISA → Unknown: 3 sailors SAISA → SAISA: 144 sailors SAISA → NEISA: 89 sailors SAISA → MAISA: 67 sailors SAISA → PCCSC: 9 sailors SAISA → SEISA: 8 sailors SAISA → MCSA: 7 sailors SAISA → Unknown: 3 sailors NWISA → NWICSA: 74 sailors NWISA → NEISA: 32 sailors NWISA → PCCSC: 25 sailors NWISA → MAISA: 12 sailors NWISA → SAISA: 8 sailors NWISA → SEISA: 2 sailors NWISA → MCSA: 2 sailors NWISA → Unknown: 1 sailors SEISA → SAISA: 24 sailors SEISA → SEISA: 22 sailors SEISA → MAISA: 14 sailors SEISA → NEISA: 11 sailors SEISA → MCSA: 2 sailors SEISA → PCCSC: 1 sailors SEISA → Unknown: 1 sailors Unknown 723 NESSA 717 MASSA 513 MISSA 490 PCISA 489 SAISA 327 NWISA 156 SEISA 75 NEISA 1100 MAISA 812 SAISA 553 PCCSC 405 MCSA 344 NWICSA 142 SEISA 94 Unknown 40 ISSA (origin) ICSA (destination)

"Unknown" is a real data gap, not a category — 723 of 3490 bridges (21%) come from an ISSA school with no conference tag in the database, not from sailors outside the conference system.

Average change by conference pair

ICSA conference (destination) by row, ISSA conference (origin) by column. Mean rating change, cell count in parentheses.

MASSA MISSA NESSA NWISA PCISA SAISA SEISA Unknown
MAISA -0.040n=81 -0.017n=30 +0.040n=46 +0.058n=5 -0.017n=26 +0.038n=23 -0.028n=3 +0.010n=39
MCSA +0.031n=5 +0.002n=52 +0.022n=5 — — — — -0.025n=14
NEISA -0.059n=46 -0.028n=34 +0.022n=115 -0.039n=10 +0.004n=39 +0.014n=46 -0.029n=4 +0.023n=36
NWICSA — -0.004n=1 — -0.018n=22 +0.129n=2 — — +0.025n=9
PCCSC +0.008n=11 +0.059n=6 +0.080n=14 -0.027n=8 +0.018n=29 -0.032n=1 — +0.149n=10
SAISA -0.017n=20 -0.015n=12 +0.019n=19 -0.059n=4 +0.097n=2 -0.001n=19 +0.007n=6 +0.025n=18
SEISA -0.071n=3 -0.036n=3 +0.043n=5 — -0.010n=3 — +0.059n=3 +0.073n=3
Unknown -0.165n=1 -0.016n=1 -0.059n=1 — — — — -0.059n=1
rating drops no data rating rises

Which colleges get the biggest incoming jump

Schools with at least 3 tracked incoming transitions, ranked by average rating change.

Lowest (still ≥3 sailors):

Which high schools produce the biggest jump

High schools with at least 3 tracked outgoing transitions, ranked by average rating change of their graduates.

Lowest (still ≥3 sailors):

Read the other pieces

College recruiting guide ICSA rankings