Tick bars and time bars answer different questions
A time chart groups observations by clock interval. A tick chart groups them by count, so its bars arrive faster during active trading and more slowly when activity falls. This changes the observations supplied to an indicator even when you leave its settings unchanged.
- Illustrative example: suppose 100 ticks arrive in 10 seconds, then the next 100 take two minutes. Both groups fill one 100T bar, despite their different durations. This is hypothetical data, not an observed market test.
- For a hypothetical 20-bar average on 100T, twenty full bars contain 2,000 ticks. Twenty one-minute bars cover twenty minutes. Equal lengths therefore do not create equivalent signals.
- Tick bars reset at a new trading session, so the prior session can end with a partial group. Keep session boundaries in the comparison record.
| Question | Time chart | Tick chart |
|---|---|---|
| What defines a bar? | A fixed time interval | A chosen count of successive ticks |
| What varies? | Activity within each interval | Elapsed time within each bar |
| What does a 20-bar lookback represent? | Twenty time intervals | Twenty groups of ticks |
| What should a comparison preserve? | Symbol, session, inputs, and dates | The same context, plus the tick interval |