Does a Support Line Make a Rebound More Likely?
Version 1.0 · report 2026-09-10 · study recorded 2026-07-08

QUESTION AND FINDING
A support line marks where prices recovered before. In this test, it did not make the next recovery more likely: dips near a line bounced less often than dips without one nearby. Past turning points did not give us the reassurance the drawing seemed to offer.

METHOD
Study universe: Selected core group of 50 stocks and exchange-traded funds; not a random market-wide sample.
Line construction: Recreated older charts with the automatic line tool, keeping its original fitted support lines instead of shifting them toward Fibonacci levels.
Comparison: Dips near support lines versus dip bars without a nearby line. The note records matching on dip depth and trend mix; the detailed matching output is not included in this edition.
Measured outcome: Counted a rebound when price rose from the dip low by at least twice its recent average range within six weeks or six months. This does not simulate a purchase, sale or trading costs.
Time split: Monthly: later sample begins 2016, within a 240-bar replay window. Weekly: later sample begins 2022, within a 500-bar window. Exact observation endpoints are unavailable in the saved summary.
Available evidence: Four summary rates and observation counts in a dated research note, plus the code used to collect the observations. The original rows and detailed comparison work were not located for this edition.

SOURCE
Source: TradingPal's research notes from July 8, 2026. The download contains four summary results saved in those notes, not a list of every price movement we studied.

LIMITATIONS
- These are exploratory historical comparisons, not papers reviewed by independent academic experts or a forecast of the next trade. They do not measure a complete trading strategy's return.
- The study used a selected group of 50 stocks and funds. It was not a random sample of the whole market, and failed or delisted businesses were not fully represented. This can change the picture.
- Several observations can come from the same security or from overlapping periods. They are not independent coin flips. The saved summaries do not provide a confidence interval that accounts for that overlap, so we do not claim statistical significance.
- The July 8, 2026 research notes preserve the reported percentages and selected group counts. This edition does not include the original observation-by-observation dataset or an independently repeated analysis. Exact first and last observation dates are not preserved in those summaries.
- This comparison was observational. Matching some features cannot make the two groups identical or remove every alternative explanation. The detailed matching output is not available in this edition.
- Only weekly and monthly results are reported. They do not establish what happens in daily or intraday trading. A six-week rebound rate should not be treated as directly comparable to a six-month rate.
- The study corrected an early comparison that put random lines on the same dip bars. Because those rows share the same future prices, that test cannot reveal whether having a line matters. This report uses the later no-nearby-line comparison recorded in the research note.

CITATION
TradingPal Research (2026-09-10). Does a Support Line Make a Rebound More Likely? Version 1.0. Historical study recorded 2026-07-08. https://tradingpal.io/learn/research/trendline-support-bounce-study