This article corrects:

  1. Statistical methods for assessing interchangeability of biosimilars Volume 32, Issue 3, 442–448, Article first published online: 17 August 2012

I would like to make several corrections to the paper titled ‘Statistical methods for assessing interchangeability of biosimilars’ by Chow, Yang, Starr and Chiu, Statistics in Medicine.

In Section 4.2, the symbols for estimator should be used for clarity in the steps illustrating how to derive totality biosimilarity index, that is,

Step 1.

Obtain math formula, the biosimilarity index for the ith domain;

Step 2.

Define the totality biosimilarity index as math formula, where wi is the weight for the ith domain, where i = 1, … ,k (number of domains); and

Step 3.

Claim biosimilarity if the 95% confidence lower bound of math formula is greater than a prespecified value math formula.

In Section 4.3, the switching index should be defined as math formula, the smallest order of the biosimilarity indices. Thus, probability density function of the defined switching index math formulais given by

display math

And the expected value and the variance of SI can be given by

display math


display math

where math formula denoted as the second raw moment of SI.

When the observations are dependent and/or from different distribution, the nonparametric bounds as obtained in [15] is

display math

which yields

display math

where sample size n = 4.

In Section 4.4, the first sentence should have read, ‘A similar idea can be applied to develop ___SI_alternating index (AI) under an appropriate study design.’

The authors apologize for the oversight.