Difference between revisions of "Splitsal assumptions"
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| − | The [[Splitsal]] program is based on the assumption that the distribution of weights in the turnoff group is a normal distribution. A normal distribution is defined by the mean (average) and standard deviation (SD). In a normal distribution, 95 percent of the observations (weights) lie within 1.96 standard deviations of the mean. The Splitsal program displays this range and users can look at these ranges to judge if the standard deviation should be increased or decreased to make the range fit their situation. | + | The [[Splitsal]] program is based on the assumption that the distribution of weights in the turnoff group is a [[Splitsal_assumptions#Normal_Distribution|normal distribution]]. A normal distribution is defined by the mean (average) and standard deviation (SD). In a normal distribution, 95 percent of the observations (weights) lie within 1.96 standard deviations of the mean. The Splitsal program displays this range and users can look at these ranges to judge if the standard deviation should be increased or decreased to make the range fit their situation. |
Please note that in a normal distribution, the distribution each side of the mean is the same. The curve of distributions is bell-shaped with each side a mirror image of the other. If a group of turnoff cattle does NOT fit this distribution, then SPLITSAL will NOT give reasonable estimates of turnoff proportions and weights. | Please note that in a normal distribution, the distribution each side of the mean is the same. The curve of distributions is bell-shaped with each side a mirror image of the other. If a group of turnoff cattle does NOT fit this distribution, then SPLITSAL will NOT give reasonable estimates of turnoff proportions and weights. | ||
Revision as of 01:48, 8 July 2020
The Splitsal program is based on the assumption that the distribution of weights in the turnoff group is a normal distribution. A normal distribution is defined by the mean (average) and standard deviation (SD). In a normal distribution, 95 percent of the observations (weights) lie within 1.96 standard deviations of the mean. The Splitsal program displays this range and users can look at these ranges to judge if the standard deviation should be increased or decreased to make the range fit their situation.
Please note that in a normal distribution, the distribution each side of the mean is the same. The curve of distributions is bell-shaped with each side a mirror image of the other. If a group of turnoff cattle does NOT fit this distribution, then SPLITSAL will NOT give reasonable estimates of turnoff proportions and weights.
Once the lead or the tail off the mob has been removed, the distribution, if originally “normal” can no longer be “normal”. Thus the Splitsal program applies only to a mob which has not previously had a cut taken out of it (other than perhaps a random cut).
The Splitsal program might also be used to estimate proportions of heifers reaching puberty at a particular age under different growth rate regimes, where the cut-off weight is used to represent expected weight at puberty.