Notice

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There are two main reasons that this document does not use third party package.

• We do not know which formulas they use behind the scene and sometimes it is hard to retrieve data.

• We could avoid technical difficulties.

• We do not have to keep up to date every time that third party changes their package.

• The document uses formulas from the book and these formulas have a long history with statistic which means they are consistent over time. We could write our third party package based on these formulas.

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The way that R round number is slightly differen than the book.

round(1.5, 0)

## [1] 2

round(.15,1)

## [1] 0.1

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To have a better understanding about how round() works, we could read the instruction from help()

help(round)

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