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2. The most pronounced trend was a persistent negative skewness (an excess of poor producers) associated with a positive kurtosis (an excess of individuals about the mean) and a marked deficiency of high producers.
3. Truncation of these populations at two or one phenotypic standard deviation below the mean tended to reduce the asymmetry but at the expense of the kurtosis which frequently became significantly negative.
4. The greatest departures from normality were observed in the earlier parts of the recording period.
5. A considerable degree of heterogeneity of variance among hatches within strain/years was observed and it is considered that this is largely due to the asymmetry.
6. Negative skewness in the distribution of egg production appears to be a widespread phenomenon and is considered to be due more likely to non‐random environmental factors than fixation of recessive genes.
7. Predictions of progress based on the normal curve must tend to overestimate what is realised and the abnormality observed, which appears to be general, must have negative implications for the accuracy of estimation of biological parameters. 相似文献
2. The standard deviation of the difference between the predicted amount of water and the amount found by analysis of an independent sample of carcass homogenate was 1.8% of the mean carcass weight.
3. Accuracy of prediction was scarcely affected by taking account of the mineral content of the carcass and was unaffected by fat content. 相似文献