REPEATABILITY EVALUATION OF A DAIRY FARM-MANAGEMENT QUESTIONNAIRE

The purpose of the research reported in this paper was to examine the repeatability of a dairy farm management questionnaire. The questionna ire was used in a study of the effects of dairy farm management and bu lk tank milk protein concentration (BTMPC). The repeatability was stud ied by a simple test-retest design and was incorporated into the overa ll design of the management-bulk tank milk protein project. The source population was farms in a specific region of the Netherlands that del ivered milk without interruption from February 1987 onward, and had an nual-milk quotas of at least 250 000 kg. Repeatabilities of categorica lly scaled questionnaire items were estimated by the intraclass kappa coefficient. Repeatabilities of continuous-scaled items were estimated by Pearson's intraclass correlation coefficient. The standard error o f each coefficient was estimated via a jackknife procedure. Influence of the following factors on question repeatability was examined: metho d of questionnaire administration, type of question, category of dairy farm management, and stratum from which the farms were sampled. The s tudy also investigated the effect of dichotomization of polytomous res ponse data on repeatability. Seventy-one percent of the questionnaire items ultimately introduced into the crude analysis of the farm manage ment-BTMPC study had chance-corrected repeatability coefficients great er than or equal to 0.40. Sixty-nine percent of the items had coeffici ents greater than or equal to 0.50. Repeatability quality of the quest ionnaire was judged to be adequate and recommendations are made for da iry farm management questionnaire formulation.