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Next: win rate is only half the story
Expectancy combines win rate with the size of wins and losses.
What is included
- What it is, in plain words
- The formula or mechanism, with exact arithmetic
- How it hits grid, martingale and DCA bots
- A check you can run before you switch a bot on
Who it is for
- People who run or plan to run a trading bot
- Anyone reading a backtest or a bot sales page
- Readers who want the numbers, not the pitch
- Not advice, and not a signal service
Key facts
- Sierra Chart is a platform where a bot or strategy is written, tested and run. This page explains the general method, not the product's current features.
- A bot is only as trustworthy as its test. Before relying on any result here, check costs, fills, data and timing, and keep a stretch of data the rule never saw.
- The worked example on this page uses made-up numbers, checked in node on 31 Oct 2026. It shows the arithmetic, not how any product performs.
- Prices, fees, markets, versions, limits and supported languages change and belong to the vendor. We state none of them. Check the vendor's current pages.
- Start on a simulated account, keep stops where they still work if the bot stops, and move to real money only in very small steps, if at all.
What it is
Sierra Chart is a desktop charting and trading platform used by active futures traders. Platforms in this group tend to be customised in a compiled language: a custom study, which can draw, calculate or send orders, is written in C++ against the platform's own interface, built into a library and loaded by the program. Some also offer a spreadsheet-style way to build simple systems without writing code.
The platform connects to data and trade services that are separate from the platform itself, so the data you test on, the data you trade on and the service that carries your orders can each be different companies with their own terms. Which services it supports and what each costs is for the vendors to say. Check their current pages. This page explains how it works in general terms. We have not tested it for this page. Check the vendor's current terms.
How a bot connects here
The connection style is built-in scripting through compiled studies, with the platform bridging to a separate trade service.
- Compiled code. A study is built, then loaded. A programming error can affect the whole platform, not only your study, so test on a simulated account.
- Replay. Platforms of this kind can replay recorded data at a chosen speed, which lets a study run as if live. How faithful that is depends on the data recorded.
- Automation toggle. A study that is only calculating is different from one allowed to send orders. Know the setting.
- Separate data and trade feeds. A mismatch between them is a source of odd fills.
Worked example: how many trades is enough?
Replay and short data windows produce few trades, and few trades mean a noisy win rate. Take a made-up test that shows a 55% win rate. The standard error is sqrt(p x (1 - p) / n). A rough 95 percent range is the observed rate plus or minus 1.96 standard errors, using a normal approximation that is itself loose for very small samples. Numbers are made up and checked in node.
| Trades in the test | Standard error | Low end | High end | Plus or minus |
|---|---|---|---|---|
| 20 | 11.1% | 33% | 77% | 22% |
| 40 | 7.9% | 40% | 70% | 15% |
| 100 | 5.0% | 45% | 65% | 10% |
| 400 | 2.5% | 50% | 60% | 5% |
After 20 trades a 55% win rate is compatible with a true rate anywhere from about 33% to 77%. That includes rates below 50 percent. After 400 trades the range narrows to about 50% to 60%. A win rate also says nothing about the size of wins against losses; see expectancy and the win rate calculator. The practical lesson is to gather more trades, over different market conditions, before reading anything into a replay.
What to verify before trusting a backtest here
These checks apply to any platform of this kind. The answers come from the vendor's current documentation and from your own tests, not from this page.
| Check | Why it matters |
|---|---|
| How much data and what kind | Tick data and bar data give different fills. Check the depth of the history. |
| Replay faithfulness | Replay at high speed or from coarse data may not match live behaviour. |
| Number of trades in the test | Few trades means a noisy result. Do the arithmetic above. |
| Costs and slippage | Enter honest costs. |
| Study built and loaded cleanly | Rebuild after any change, and check the study is the version you meant to run. |
| Trade service behaviour | Order handling is the service's, not the chart's. Test it on a simulated account. |
How bots break on this kind of platform
- Crash or freeze. A compiled study can take the platform down with a position open.
- Version confusion. The loaded study is not the one you tested.
- Data differences. Recorded data versus the live feed.
- Too few trades. A result that cannot be told apart from luck.
- Connection loss. The platform and the trade service lose each other. See slippage.
A safe order of work
Backtest with honest costs, forward test on new data, run on a simulated account for weeks, then trade a very small size and compare each step with the one before. See forward testing and paper trading.
What this page does not tell you
It does not tell you whether the product is suitable, what it costs, or how it behaves today. Those change and belong to the vendor. It does not give a strategy to trade. This page explains how it works in general terms. We have not tested it for this page. Check the vendor's current terms.
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FAQ
Frequently Asked Questions
What language is used for custom studies on Sierra Chart?
Platforms of this kind use compiled C++ for custom studies. Check the vendor for the current interface and any alternatives.
Can a replay prove a strategy works?
No. It shows how a rule behaved on recorded data, usually a small sample. See forward testing for the next step.
Does a good Sierra Chart backtest mean a bot will make money?
No. A backtest shows how a rule behaved on past data under its assumptions. Costs, fills, data and luck can all make live results different.
Should I test on a simulated account before real money?
Yes, as a general practice. A simulated account tests your code and your plumbing. Its fills are usually kinder than real ones, so it does not prove a rule works.
Have you tested Sierra Chart?
No. This page explains how it works in general terms and we have not tested it for this page. Check the vendor's current terms.
Are the numbers on this page real?
Example numbers are made up to show how the maths works, and the page says so. A figure only counts as exact when the page says it was calculated on a stated date. Nothing you enter in a calculator leaves your browser.
Can I use this to decide whether to run a bot?
It can show whether a bot's numbers hold together and how much an account can lose. It cannot say what the market will do, and it is not advice. Use it to ask better questions, then read the terms of your own broker or exchange.
Is this financial advice?
No. It is general education. The numbers are made up and it does not consider your situation.
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