Question

Using the chickwts dataframe, compute the 10th, 30th, and 90th percentiles of all the chick weights and then use tapply to determine which feed type is associated with the highest sample variance of weights. Use rStudio and the dataframe provided within rStudio named chickwts

Answer 1

The following codes are run to get the required output:

> attach(chickwts)
The following objects are masked from chickwts (pos = 3):

feed, weight

The following objects are masked from chickwts (pos = 4):

feed, weight

> data=chickwts
> quantile(data[,1],c(0.10,0.30,0.90))
10% 30% 90%
153 217 359
> tapply(data[,1],INDEX=data[,2],FUN=var)
casein horsebean linseed meatmeal soybean sunflower
4151.720 1491.956 2728.568 4212.091 2929.956 2384.992

Hence, Meatmeal feed type  has the highest sample variance in the data.

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