Moving averages, RSI, and MACD
A critical look at what the three most-used indicators measure, the risks of lag and misuse, a combined-signal example, and the myth of a “best indicator.”
A moving average (MA) plots the average price over a period, smoothing noise and showing trend. RSI measures the speed of a move on a 0–100 scale and flags extreme zones. MACD tracks momentum change through the difference between two moving averages. All three are derived from price, so they follow it rather than lead it.
Why it matters
Beginners treat an indicator as a “buy/sell button.” But indicators are summaries, and they all lag. Using them without knowing what they measure and where they mislead leads to mistaking noise for signal.
Three indicators, three measurements
| What it measures | Typical failure | |
|---|---|---|
| Moving average | Trend direction and slope | Constant crossover signals in a flat market |
| RSI | Speed of a move / extremes | Stays “extreme” for long in a strong trend |
| MACD | Change in momentum | Lags at sharp reversals |
Schematic oscillator
- Upper band: the “overbought” zone
- Lower band: the “oversold” zone
- Staying in a band: can signal a strong trend
- An extreme does not mean an automatic reversal
A combined-signal example
| Trend filter | Price above the 200-day MA (upward bias) |
|---|---|
| Timing | RSI turning up from oversold |
| Confirmation | MACD crossing its signal line upward |
| Risk | Invalidation: price closes below the recent low |
Aligning three complementary conditions, instead of one indicator, strengthens the signal — yet still guarantees nothing.
The most common mistake is optimising an indicator to find its “perfect setting.” The setting that best fits the past is not the one that best fits the future; this opens the door to overfitting.
The “best indicator” myth
| “If I find the right indicator, I will win.” | No indicator is superior alone; the value is in the usage rule and risk management. |
| “More indicators means more certainty.” | Most indicators derive from the same price; stacking them can be repetition, not confirmation. |
Indicators are computed from past data and lag; they guarantee no gain. Too many indicators can create a false sense of confidence.
Now that you see what indicators are and their limits, learn to turn them from vague ideas into explicit rules. Move on to strategy rules.