Discussion 05 - Matrix

# Discussion 05 - Matrix - Masanao Yajima Your reader went...

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Masanao Yajima

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Your reader went very easy on you since this is the first time. But the stake is going to get higher as we go on. Specially if you are unsure of for loops and variable assignment make sure you are able to use them since you will need it for the next homework.
# moment around 0 MomentZero <- function( x ) { moments <- rep( NA, 4 ) nx <- length( x ) for( i in 1:4 ){ moments[i] <- sum( x ^ i ) / nx } return( moments ) } # moment around the mean MomentMean <- function( x ) { moments <- NULL nx <- length( x ) mx <- mean( x ) for( i in 1:4 ) { moments <- c(moments, sum( ( x - mx ) ^ i ) / nx ) } return( moments ) } # skewness and kurtosis SkewKurtosis <- function( x ){ mu <- MomentMean( x ) skewness <- mu[3] / ( mu[2] ^ ( 3 / 2 ) ) kurtosis <- mu[4] / ( mu[2] ^ 2 )-3 result <- c( skewness, kurtosis ) names( result ) <- c( "skewness,", " kurtosis" ) return( result ) }

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# core function that is more general SampleMoment<- function( x, moment = c( 1:4 ), center = 0 ) { nx <- length( x ) return( sapply( moment, function( m ) { sum( ( x - center ) ^ m ) / nx } ) )
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## This note was uploaded on 01/14/2011 for the course STATS 102A 102A taught by Professor Jandeleeuw during the Fall '10 term at UCLA.

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Discussion 05 - Matrix - Masanao Yajima Your reader went...

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