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Table 2 Statistical methods

From: Radiotherapy versus low-dose tamoxifen following breast-conserving surgery for low-risk and estrogen receptor-positive breast ductal carcinoma in situ: an international open-label randomized non-inferiority trial (TBCC-ARO DCIS Trial)

α: type 1 error—> 0.05

β: power—> 0.9

Assume (no-RT) low risk IBTR: 6%

Assume that Tamoxifen = RT = 6%

Assume a margin (IBTR difference: 5%)

N = (Zα + Zβ)2xS2/Δ2 = 385 (per arm)

N = 2 * n = 770 (total)

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BMC Cancer

ISSN: 1471-2407

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