I Tracked 100 Predictions. The Ugly Spreadsheet That Fixed My Process.

18+ only. Betting carries a real risk of losing money. Set a deposit limit before you start, and stop if it stops being fun.

The spreadsheet is not impressive. It has seven columns, no charts and no macros. It is the single most useful thing in this series, and almost nobody keeps one, because it does something nobody enjoys: it tells you the truth about your own opinions.

The seven columns

Four fields before, three after. That is the whole system. It takes about ninety seconds a match.

The three numbers it produces

1. Calibration. Group your predictions by confidence band and check the hit rate in each. Your 60% calls should win about 60% of the time; your 80% calls about 80%.

Almost nobody is calibrated at first. The typical pattern is that high-confidence calls underperform badly — you are most wrong exactly where you are most sure, which is also where people stake most. Fixing that one thing changes more than any tipping service ever will.

2. Mechanism accuracy. Of the predictions that won, in how many did your stated reason actually happen?

A high win rate with a low mechanism rate is the most dangerous result in the whole spreadsheet. It means you are being rewarded for reasoning that is not working, and you will keep doing it until it costs you badly.

3. Closing line value. Did you take a better price than the market closed at?

This is the professional's metric, and the reason is statistical: CLV stabilises far faster than profit does. You can beat the closing line consistently and still be down over fifty bets, because fifty is a small number. Profit over a short run is mostly noise; CLV over the same run is signal.

What 100 rows usually reveals

Three findings show up so consistently that you can almost predict them:

Your confidence is inflated. The 80% band lands somewhere in the 60s. This is human and universal; the fix is to shade every stated probability towards 50 until the data says otherwise.

Your good reads cluster. One league, one sport, or one situation — a specific kind of matchup — carries almost all of your genuine edge. Everything outside it is roughly a coin flip with a margin attached.

Volume is the enemy. People bet the most matches on the days they know the least. The spreadsheet makes that pattern visible in a way that nothing else does.

The point of the spreadsheet is not to prove you are good. It is to find the small part of your judgement that actually is, and to stop paying for the rest.

What to do with the findings

One practical footnote before you open accounts anywhere: a tracking spreadsheet plus several book logins is a lot of reused credentials in one place. Our sister site's write-up of the password rules NIST now says to stop following is the short version of doing that part properly.

The staking side is not optional and is covered fully in sports betting bankroll management. The most common errors are catalogued in sports betting mistakes to avoid, and the value framework in how to find value bets and expected value explained.

If you use tips or models instead

Run the same spreadsheet on them. A tipster or a model that cannot show calibration and CLV over a real sample is asking you to trust a highlight reel of their best month.

Our test for that is how to spot a trustworthy tipster, and the machine version has exactly the same weaknesses — see The Oracle: how AI predicts sports results.

The honest ending

Most people who keep this spreadsheet for 100 rows conclude that they should bet less, on fewer matches, for smaller amounts. That is not a failure of the exercise — it is the exercise working.

The margin is real, it is charged on every bet, and beating it consistently is genuinely hard. Treating this as paid entertainment with a known cost is the only sustainable version for almost everyone.

18+ only. If gambling is causing harm, stop and contact a national support line in your country.

Where the partner links sit. The "price taken" and "closing price" columns need somewhere to read a price from, and reading it from two books is better than one. We hold partner accounts with Thunderpick Sports and V.Vegas Sportsbook — partner links, both of them, and both subject to their own country eligibility terms. Nothing in this article is a recommendation to increase your stake. 18+, terms apply, your stake is at risk.

Back to Part 1.

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