Differences

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--- c:ma:2019:lecturer [2019/10/01 23:10] – [anova: mtcars] hkimscil
+++ c:ma:2019:lecturer [2019/10/04 11:28] (current) – [anova: mtcars] hkimscil
@@ Line 93: / Line 93: @@
 [13] 21.4
-> data.frame(mdata)
-Error in (function (..., row.names = NULL, check.rows = FALSE, check.names = TRUE,  :
-  arguments imply differing number of rows: 19, 13
 > stack(mdata)
    values ind
@@ Line 130: / Line 127: @@
    15.0   1
    21.4   1
-> mdat
-Error: object 'mdat' not found
 > mdata
 $`0`
@@ Line 141: / Line 136: @@
 [13] 21.4
-> mdata[[1\]]
-Error: unexpected input in "mdata[[1\"
-> mdata[[1]]
- [1] 21.4 18.7 18.1 14.3 24.4 22.8 19.2 17.8 16.4 17.3 15.2 10.4
-[13] 10.4 14.7 21.5 15.5 15.2 13.3 19.2
-> var(mdata[[1]])
-[1] 14.6993
-> length(mdata[[1]])
-[1] 19
-> md.df <- length(mdata[[1]]) -1
-> md.df
-[1] 18
-> md.n <- length(mdata[[1]])
-> md.var <- var(mdata[[1]])
-> md.var
-[1] 14.6993
-> md.ss <- md.var*md.df
-> md.ss
-[1] 264.5874
-> md2.df <- length(mdata[[2]]) -1
-> md2.n <- length(mdata[[2]])
-> md2.var <- var(mdata[[2]])
-> md2.ss <- md2.var*md2.df
-> md.ss+md2.ss
-[1] 720.8966
-> (md.ss+md2.ss)/(md.df+md2.df)
-[1] 24.02989
-> pvar <- sqrt((md.ss+md2.ss)/(md.df+md2.df))
-> pvar
-[1] 4.902029
-> pvar <- (md.ss+md2.ss)/(md.df+md2.df)
-> pvar/nd.n
-Error: object 'nd.n' not found
-> pvar/md.n
-[1] 1.264731
-> pvar/md2.n
-[1] 1.848453
-> a <- pvar/md.n
-> b <- pvar/md2.n
-> tscore <- sqrt(a+b)
-> tscore
-[1] 1.764422
 > t.test(mpg~am, data=mtcars)
@@ Line 196: / Line 149: @@
 .14737        24.39231
-> t.test(mpg~am, data=mtcars, equal.var=T)
-	Welch Two Sample t-test
-data:  mpg by am
-t = -3.7671, df = 18.332, p-value = 0.001374
-alternative hypothesis: true difference in means is not equal to 0
-percent confidence interval:
- -11.280194  -3.209684
-sample estimates:
-mean in group 0 mean in group 1
-.14737        24.39231
-> ?t.test
 > t.test(mpg~am, data=mtcars, var.equal=T)
@@ Line 291: / Line 230: @@
    return(out)
 }
-stats <- stats4each(mtcars$hp, mtcars$cyl)
+library(MASS)
+tempd <- iris
+x <- tempd$Species
+y <- tempd$Sepal.Width
+tempd <- mtcars
+x <- tempd$gear
+y <- tempd$mpg
+tempd <- mtcars
+x <- tempd$am
+y <- tempd$mpg
+x <- factor(x)
+dfbetween <- nlevels(x)-1
+stats <- stats4each(y, x)
 stats
 sswithin <- sum(stats[5,])
-sstotal <- var(mtcars$hp)*(length(mtcars$hp)-1)
+sstotal <- var(y)*(length(y)-1)
 ssbetween <- sstotal-sswithin
-round(sswithin,0)
+round(sswithin,2)
-round(ssbetween,0)
+round(ssbetween,2)
-round(sstotal,0)
+round(sstotal,2)
 dfwithin <- sum(stats[4,])
-dfbetween <- 3-1
+dftotal <- length(y)-1
-dftotal <- length(mtcars$hp)-1
 dfwithin
@@ Line 314: / Line 271: @@
 mstotal <- sstotal / dftotal
-round(mswithin,0)
+round(mswithin,2)
-round(msbetween,0)
+round(msbetween,2)
-round(mstotal,0)
+round(mstotal,2)
 fval <- round(msbetween/mswithin,2)
 fval
-siglevel <- pf(q=36.18, df1=2, df2=29, lower.tail=FALSE)
+siglevel <- pf(q=fval, df1=dfbetween, df2=dfwithin, lower.tail=FALSE)
 siglevel
-mod <- aov(mtcars$hp~mtcars$cyl, data=mtcars)
+mod <- aov(y~x, data=tempd)
 summary(mod)
 </code>
+====== cor ======
+<code>
+attach(mtcars)
+cor(mpg, hp)
+mycor <- cov(mpg,hp)/(sd(mpg)*sd(hp))
+mycor
+sp <- cov(mpg,hp)*(length(mtcars$hp)-1)
+ssx <- var(mpg)*(length(mtcars$mpg)-1)
+ssy <- var(hp)*(length(mtcars$hp)-1)
+mycor2 <- sp/sqrt(ssx*ssy)
+mycor2
+mycor2 == mycor
+mycor == cor(mpg,hp)
+mycor2 == cor(mpg,hp)
+</code>