Hostname: page-component-76fb5796d-25wd4 Total loading time: 0 Render date: 2024-04-26T08:10:21.065Z Has data issue: false hasContentIssue false

Economic values under inappropriate normal distribution assumptions

Published online by Cambridge University Press:  09 February 2012

A. Sadeghi-Sefidmazgi*
Affiliation:
Department of Animal Science, University of Tehran, PO Box 3158711167-4111, Karaj, Iran
A. Nejati-Javaremi
Affiliation:
Department of Animal Science, University of Tehran, PO Box 3158711167-4111, Karaj, Iran
M. Moradi-Shahrbabak
Affiliation:
Department of Animal Science, University of Tehran, PO Box 3158711167-4111, Karaj, Iran
S. R. Miraei-Ashtiani
Affiliation:
Department of Animal Science, University of Tehran, PO Box 3158711167-4111, Karaj, Iran
P. R. Amer
Affiliation:
AbacusBio Limited, PO Box 5585, Dunedin, New Zealand
Get access

Abstract

The objectives of this study were to quantify the errors in economic values (EVs) for traits affected by cost or price thresholds when skewed or kurtotic distributions of varying degree are assumed to be normal and when data with a normal distribution is subject to censoring. EVs were estimated for a continuous trait with dichotomous economic implications because of a price premium or penalty arising from a threshold ranging between −4 and 4 standard deviations from the mean. In order to evaluate the impacts of skewness, positive and negative excess kurtosis, standard skew normal, Pearson and the raised cosine distributions were used, respectively. For the various evaluable levels of skewness and kurtosis, the results showed that EVs can be underestimated or overestimated by more than 100% when price determining thresholds fall within a range from the mean that might be expected in practice. Estimates of EVs were very sensitive to censoring or missing data. In contrast to practical genetic evaluation, economic evaluation is very sensitive to lack of normality and missing data. Although in some special situations, the presence of multiple thresholds may attenuate the combined effect of errors at each threshold point, in practical situations there is a tendency for a few key thresholds to dominate the EV, and there are many situations where errors could be compounded across multiple thresholds. In the development of breeding objectives for non-normal continuous traits influenced by value thresholds, it is necessary to select a transformation that will resolve problems of non-normality or consider alternative methods that are less sensitive to non-normality.

Type
Full Paper
Copyright
Copyright © The Animal Consortium 2012

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Abdel-Azim, GA, Berger, PJ 1999. Properties of threshold model predictions. Journal of Animal Science 77, 582590.CrossRefGoogle ScholarPubMed
Amer, PR 2006. Approaches to formulating breeding objectives. Proceedings of the 8th World Congress on Genetics Applied to Livestock Production, Belo Horizonte, Brazil.Google Scholar
Amer, PR, Hofer, A 1994. Optimum bias in selection index parameters estimated with uncertainty. Journal of Animal Breeding and Genetics 111, 89101.CrossRefGoogle ScholarPubMed
Amer, PR, Lowman, BG, Simm, G 1996. Economic values for reproduction traits in beef suckler herds based on a calving distribution model. Livestock Production Science 46, 8596.CrossRefGoogle Scholar
Amer, PR, Simm, G, Keane, MG, Diskin, MG, Wickham, BW 2001. Breeding objectives for beef cattle in Ireland. Livestock Production Science 67, 223239.CrossRefGoogle Scholar
Azzalini, A 1985. A class of distributions which includes the normal ones. Scandinavian Journal of Statistics 12, 171178.Google Scholar
Eriksson, S, Näsholm, A, Johansson, K, Philipsson, J 2004. Genetic relationships between calving and carcass traits for Charolais and Hereford cattle in Sweden. Journal of Animal Science 82, 22692276.CrossRefGoogle ScholarPubMed
Hoeschele, I, Gianola, D, Foulley, JL 1987. Estimation of variances components with quasi-continuous data using Bayesian methods. Journal of Animal Breeding and Genetics 104, 334349.CrossRefGoogle Scholar
Hou, Y, Madsen, P, Labouriau, R, Zhang, Y, Lund, MS, Su, G 2009. Genetic analysis of days from calving to first insemination and days open in Danish Holsteins using different models and censoring scenarios. Journal of Dairy Science 92, 12291239.CrossRefGoogle ScholarPubMed
Meijering, A 1980. Beef crossing with Dutch Friesian cows: model calculations on expected levels of calving difficulties and their consequences for profitability. Livestock Production Science 7, 419436.CrossRefGoogle Scholar
Meijering, A 1986. Dystocia in dairy cattle breeding with special attention to sire evaluation for categorical traits. PhD, Wageningen Agricultural Univ.Google Scholar
Meijering, A, Gianola, D 1985. Linear versus nonlinear methods of sire evaluation for categorical traits: a simulation study. Genetic Selection Evolution 17, 115132.CrossRefGoogle ScholarPubMed
Pearson, K 1916. Mathematical contributions to the theory of evolution, XIX: second supplement to a memoir on skew variation. Philosophical Transactions of the Royal Society Series A: Mathematical, Physical and Engineering Sciences 216, 429457.Google Scholar
Ponzoni, RW, Newman, S 1989. Developing breeding objectives for Australian beef cattle production. Animal Production 49, 3547.Google Scholar
Quinton, VM, Wilton, JWand Robinson, AB 2010. Selection of terminal sires and dams for meat producing animals sold under a grid pricing system. Proceedings of the 9th World Congress on Genetics Applied to Livestock Production, Leipzig, Germany.Google Scholar
Ramirez-Valverde, R, Misztal, I, Bertrand, JK 2001. Comparison of threshold vs linear and animal vs sire models for predicting direct and maternal genetic effects on calving difficulty in beef cattle. Journal of Animal Science 79, 333338.CrossRefGoogle ScholarPubMed
Sadeghi-Sefidmazgi, A, Moradi-Shahrbabak, M, Nejati-Javaremi, A, Miraei-Ashtiani, SR, Amer, PR 2011. Estimation of economic values and financial losses associated with clinical mastitis and somatic cell score in Holstein dairy cattle. Animal 5, 3342.Google Scholar
Smith, C 1983. Effects of changes in economic weights on the efficiency of index selection. Journal of Animal Science 56, 10571064.CrossRefGoogle Scholar
Surhone, LM, Tennoe, MT, Henssonow, SF 2010. Raised cosine distribution, 1st edition. LAP Lambert Academic Publishing AG & Co. KG, Germany.Google Scholar
Van der Werf, JHJ, Van der Waaij, L, Groen, A, De Jong, G 1998. Constructing an index for beef characteristics in dairy cattle based on carcass traits. Livestock Production Science 54, 1120.CrossRefGoogle Scholar
Vandepitte, WM, Hazel, LN 1977. The effect of errors in the economic weights on the accuracy of selection indexes. Annales de Genetique et de Selection Animale 9, 87103.Google ScholarPubMed
Varona, L, Moreno, C, Altarriba, J 2009. A model with heterogeneous thresholds for subjective traits: fat cover and conformation score in the Pirenaica beef cattle. Journal of Animal Science 87, 12101217.CrossRefGoogle Scholar
Wang, Y, Schenkel, FS, Miller, SP, Wilton, JW 2005. Comparison of models and impact of missing records on genetic evaluation of calving ease in a simulated beef cattle population. Canadian Journal of Animal Science 85, 145155.CrossRefGoogle Scholar
Supplementary material: File

Sadeghi-Sefidmazgi supplementary material

Appendices.doc

Download Sadeghi-Sefidmazgi supplementary material(File)
File 79.4 KB