A number of recent papers have examined measures of intra-industry trade (IIT) and related indicators such as matched and unmatched changes in trade (MCIT and UCIT) as indicators of adjustment costs associated with trade expansion or contraction. We make three contributions to this literature. First, we clarify what is meant by adjustment costs in the context of these IIT-related measures. Second, we present new measures of MCIT and UCIT. Third, we compare our measures with existing measures using some simple numerical examples and data on Irish chemicals trade. We find that previous IIT-related measures tend to overestimate the extent of MCIT, and underestimate UCIT. We also find that the extent of the bias in these measures can be substantial. Thus, they are unreliable as indicators of adjustment costs. Our measures overcome these limitations.