This book presents research on sources of errors in pig weight measurements. Three studies were conducted on a New Zealand pig farm. First, finisher pigs fed ad libitum or via a liquid feeding system were weighed four times a day over a four-day period. Results showed that standardizing weighing time reduced fluctuations in pig weights. Next, the effect of overnight feed withdrawal on reducing variation in pig weigths and growth rate was investigated. Feed withdrawal reduced variability by up to 11.5% in grower and finisher pigs, whilst the effect was inconsistent in weaner pigs. Lastly, sampling error was compared when sampling pens from batches of pigs using different sample sizes and sampling methods. Increasing the portion of randomly selected pens reduced sampling error, but in a diminishing manner. Purposive selection of two pens reduced sampling error by 64% compared with random sampling, but it introduces the risk of bias. Thus, pens should be selected at...