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sgmean 0.1.1

Bug fixes

• Critical fix: Corrected the proportional trimmed mean formula for cases where k = trim * n >= 1. The previous implementation (v0.1.0) incorrectly applied a (1 - k) discount to x[1] and x[n] for all cases, which is only correct when k < 1 (Type A distortion). For k >= 1, this produced incorrect results.

• For exact integer k >= 2, sgmean() now correctly returns the same result as mean(..., trim) (as documented and expected).

• For non-integer k > 1 (Type B distortion), sgmean() now correctly applies a fractional discount (1 - delta) to x[floor(k) + 1] and x[n - floor(k)], consistent with expression (4) of the companion article and verified against Statgraphics output.

• The fix was discovered and verified during peer review of the companion article submitted to The R Journal. The corrected implementation produces results identical to Statgraphics for all tested cases.

Verification

• Type A (n=15, trim=0.05, k=0.75): unchanged — 1499.074 (correct in v0.1.0)
• Type B (n=15, trim=0.10, k=1.50): corrected — 1365.833 (vs 1102.083 in v0.1.0)
• Control (k exact integer): corrected — now identical to mean(..., trim)

sgmean 0.1.0

• Initial CRAN release (2026-06-03).
• Implements proportional trimmed mean compatible with Statgraphics.
• Resolves Type A (k < 1) and Type B (k > 1, non-integer) distortions of base R’s mean(..., trim).

These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.
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