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Statistical modelling
Using the EXPTOT and EXP210 values and using Stats →
Summary Statistics → Summarize Contents of Variates… we can determine the statistics below, based on their lactation offtakes, firstly for all cows and secondly for the top 40 cows. We can see that the mean lactation offtake for the 'elite' 40 cows is close to 50% more than that for the total sample of 387 cows.
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Summary statistics for EXPTOT
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Number of observations
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=387
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Number of missing values
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=0
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Mean
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=347.0
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Median
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=342.0
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Minimum
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=98.0
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Maximum
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=645.0
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Lower quartile
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=290.0
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Upper quartile
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=400.8
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Summary statistics for
EXP210
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Number of observations
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=387
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Number of missing values
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=0
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Mean
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=323.0 |
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Median
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=318.0 |
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Minimum
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=107.0 |
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Maximum
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=564.0 |
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Lower quartile
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=274.0 |
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Upper quartile
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=366.8 |
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Summary statistics for EXPTOT
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Number of observations
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=40
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Number of missing values
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=0
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Mean
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=503.0 |
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Median
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=496.5 |
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Minimum
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=450.0 |
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Maximum
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=645.0 |
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Lower quartile
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=463.5 |
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Upper quartile
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=522.0 |
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Summary statistics for
EXP210
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Number of observations
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=40
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Number of missing values
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=0
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Mean
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=456.5 |
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Median
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=451.5 |
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Minimum
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=409.0 |
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Maximum
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=564.0 |
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Lower quartile
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=420.0 |
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Upper quartile
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=483.0 |
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Fourteen of the 40 'elite' cows selected on the basis of EXPTOT were from Kanyanya, nine from Ryeru, and the rest from the other herd groups. This suggests that the greatest animal variation for milk offtake may have occurred within these areas.
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