文档介绍：STATISTICAL PROCESS CONTROL CHARTS
APPLIED TO DAIRY HERD REPRODUCTION
A THESIS
SUBMITTED TO THE FACULTY OF THE GRADUATE SCHOOL
OF THE UNIVERSITY OF MINNESOTA
BY
ALBERT DE VRIES
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
BERNARD J. CONLIN AND GERALD C. SHURSON, ADVISERS
APRIL 2001
Albert de Vries 2001
The central problem in management and leadership (...)
is failure to understand the information in variation.
W. E. Deming
ABSTRACT
The objective of this research was to evaluate the design and performance of statistical process
control (SPC) charts when applied to dairy herd reproduction.
A review of the literature involving the application of SPC charts in livestock production
revealed that most papers provide an introduction to SPC charts and show examples with
livestock performance data. No studies have determined the performance of SPC charts in
livestock production.
A stochastic dynamic simulation model of a dairy herd named DASIMO was developed
to simulate the performance of SPC charts in dairy herd reproduction. This Monte Carlo model
simulates daily performance of individual dairy cows and youngstock over time using functions
for milk production, feed intake, disease, reproduction, and animal replacement. DASIMO
realistically simulated normal variability in dairy herd reproductive performance.
Various Shewhart and cusum control charts were designed for first service interval,
conception interval, estrus detection index, and conception ratio. DASIMO was used to measure
the average time to signal on the SPC charts using these four variables when estrus detection
efficiency changed. The observed false alarm rate on the SPC charts was occasionally quite
different from the target. Cusum charts typically signaled a step change faster than Shewhart
charts. The estrus d