ine whether a treatment changes how well an autistic child interacts with other children, which is measured by having experts watch the child and rate their interactions with the other children. In this case we would like to make sure that the answers don’t depend on the individual rater — that is, we would like for there to be high <em>inter-rater reliability</em>. This can be assessed by having more than one rater perform the rating, and then comparing their ratings to make sure that they agree well w