Estimation of Missing Monthly Test-Day Records

Abstract

Three methods, within herd regression, regression ignoring herd effects, and a ratio factor method, of estimating a missing monthly test-day record from preceding or succeeding known test-day records are compared. The intra-herd regression method is considered to be better than regression ignoring herd effects or the ratio factor method. The regression procedure ignoring herd effects, however, is generally less than 10% less efficient than the intra-herd method and is recommended for use, since population averages are easier to obtain and to use than are the herd averages required for the intra-herd method. Factors are presented for estimating a missing monthly test-day record by the three methods when (1) the preceding monthly record is known, (2) the succeeding monthly record is known, and (3) both preceding and succeeding records are known.