Level stakes and return

Why backing everything loses more than the book margin.

Level stakes is the plainest number in the statistics block and the one most likely to be quoted out of context. It is a measure of the prices, not a strategy.

What it is

One unit staked to win on every qualifying runner, settled at the returned starting price.

"runs":         1420,
"wins":         188,
"level_stakes": -142.60,     # units
"roi":          -0.1004      # -10.04%

No commission, no place terms, no staking plan, no ability to take a price other than SP. Those omissions are deliberate: every one of them is a decision you would make, and baking a guess at your decisions into our number would make it uncomparable between users.

Why almost everything loses

Because the book is not fair. Add the implied probabilities across a field and you get more than one; the excess is the margin, and backing everything pays it every time.

In our archive that margin averages about 117% in fields of two to seven and 133% in sixteen or more. So a blind strategy in large fields starts roughly a quarter behind before anything else happens.

This is why a level stakes figure near zero is remarkable and one at minus five percent is respectable. Comparing a strategy against zero is comparing it against something nobody can achieve.

The two numbers together

A/E and level stakes answer different questions and disagree often.

A/E	Level stakes	What happened
1.05	-8%	Beat the market slightly, but not by enough to cover the margin. Common, and not a failure.
0.95	+12%	Won less often than priced, but the winners were long ones. Usually a handful of results carrying everything. Check the win count.
1.20	+18%	Genuinely beat the prices, if the interval excludes 1.00 and the sample is large.
0.72	-51%	The 16/1 and longer band across the whole archive. Both numbers agree and the sample is half a million runners.

A/E is the better signal, level stakes is the better sanity check. A high level stakes with a low A/E means variance rather than skill, and the win count usually tells you that at a glance.

Where it is fragile

Long prices dominate it. One 100/1 winner moves a hundred-runner sample by a full unit per run. A/E is affected far less.
It is a total, not a rate. Compare roi between samples, never level_stakes.
It assumes you get SP. Anyone taking early prices does better; anyone taking a shorter price does worse.

Reading it honestly

Check runs. Under a few hundred, this number is mostly noise.
Check wins. Three winners producing a positive return is three results, not a finding.
Check a_e_range. If it spans 1.00, the level stakes figure is spanning zero too whatever it says.
Compare against the right baseline. Not zero, but what the same population of prices returns, which is what price performance gives you.

What it is genuinely good for

Ruling things out. A filter with a large sample and a level stakes at minus twenty percent is not going to become profitable with better staking, and knowing that in one request is worth more than most of what a positive number would have told you.