Learn · Three small experiments
Make a prediction.
Then question the result.
A trading rule, a hidden cost, and a fair comparison. Explore each with made-up numbers before you try your own paper replay.
About 5 minutes · No account · Progress kept on this device
Case 1 · Fictional rule
The price is up.
Should the rule buy?
This example buys only when today’s rise is at least 2% and the past hour is flat or rising. Both checks must pass.
- Today
- +3%
- Past hour
- −0.5%
What should this rule do?
The rule waits.
Case 2 · Fictional trade
The chart shows a gain.
What does the account show?
A $100 budget includes the entry fee. The price rises 1%. A fee of 0.8% and a 0.05% worse-price allowance apply on each side of the trade.
- Starting budget
- $100
- Price rise
- +1%
After these costs, profit or loss?
Count both sides of the trade.
- Gain without any costs
- +$1.00
- Effect of fees and price allowances
- Net result
Case 3 · Fictional comparison
A strategy made money.
Does that prove it was useful?
Two independent paper accounts start with the same $100, over the same made-up period. These ending values already include their stated costs.
Does the strategy’s profit alone prove it adds value?
A profit needs a fair comparison.
The strategy gained $2; holding gained $5 with the same starting capital. That gives you a better question, not a final verdict.
Their time in the market and losses along the way may differ. One fictional period cannot tell you which choice will work in a new market.
Three cases explored
Take better questions
into your next experiment.
- What does the rule actually require?
- What costs did the return leave out?
- Compared with what, at what risk?
You’ve tried each case. Keep testing these questions with a different rule or a different fictional market.
Your predictions and optional notes stay on this device unless you download them.
About your saved progress
This browser keeps your case progress, predictions and optional questions on this device. Nothing here is submitted to an account.