“…Kaiser, T.B. Hancock, unpublished data, 1998) . Articles were excluded because of the reported age of participants (mean age plus 1 SD, >6 years; n = 11 studies), the inclusion of too few participants (n = 34 studies), the inclusion of nonparents as the primary interventionists (n = 343 studies), no reported measure of communication or language (n = 66 studies), no availability in English (n = 8 studies), or no reported statistics appropriate for calculating an effect size and no additional details or no author response to a request for information (n = 226 studies).…”