paspalum <- read.table("C:/Rexamples/paspalum1data.txt", header=T)
View(paspalum)
summary(paspalum)
attach(paspalum)
by(weight, treat, function(x) summary(x))
by(weight, treat, function(x) sd(x))
boxplot(weight~treat)
by(weight, treat, function(x) stem(x))
qqnorm(weight[treat=='inocul'], main="Normal Q-Q Plot, inoculated")
qqline(weight[treat=='inocul'])
shapiro.test(weight[treat=='inocul'])
qqnorm(weight[treat=='notinoc'], main="Normal Q-Q Plot, not inoculated")
qqline(weight[treat=='notinoc'])
shapiro.test(weight[treat=='notinoc'])
t.test(weight~treat)
t.test(weight~treat, var.equal=TRUE)

--------------------- NOTE ------------------------

The first line above which reads the data from the file
"paspalum1data.txt" assumes that this file is in the directory
"C:/Rexamples".  Obey this convention or modify the command.

-------------------------- results ----------------------------------

The boxplots and normal probability plots (qqplots) requested in this
program will appear in the plot window of RStudio.  They can be saved
as pdfs or images. I have not posted them here.  These plots are
somewhat crude since I did not specify titles, labels, or such.

The remainder of this file is copied and pasted from the RStudio
command window.

--------------------------------------------------------


> paspalum <- read.table("C:/Rexamples/paspalum1data.txt", header=T)
> View(paspalum)
> summary(paspalum)
     treat        weight
 inocul :12   Min.   : 3.900
 notinoc:12   1st Qu.: 7.325
              Median :11.600
              Mean   :11.233
              3rd Qu.:13.825
              Max.   :21.800
> attach(paspalum)
> by(weight, treat, function(x) summary(x))
treat: inocul
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.
  3.900   5.125   8.600   8.975  10.650  19.700
-----------------------------------------------
treat: notinoc
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.
   6.20   11.90   13.35   13.49   15.65   21.80
> by(weight, treat, function(x) sd(x))
treat: inocul
[1] 4.638402
-----------------------------------------------
treat: notinoc
[1] 4.022993
> boxplot(weight~treat)


> the boxplots appear in the plot window of RStudio *****************

> by(weight, treat, function(x) stem(x))

  The decimal point is 1 digit(s) to the right of the |

  0 | 44
  0 | 5578
  1 | 00024
  1 |
  2 | 0


  The decimal point is 1 digit(s) to the right of the |

  0 | 69
  1 | 12234
  1 | 5567
  2 | 2

treat: inocul
NULL
-----------------------------------------------
treat: notinoc
NULL
> qqnorm(weight[treat=='inocul'], main="Normal Q-Q Plot, inoculated")
> qqline(weight[treat=='inocul'])
> shapiro.test(weight[treat=='inocul'])

	Shapiro-Wilk normality test

data:  weight[treat == "inocul"]
W = 0.9057, p-value = 0.1879

> the normal probability plot appears in the plot window of RStudio *****************

> qqnorm(weight[treat=='notinoc'], main="Normal Q-Q Plot, not inoculated")
> qqline(weight[treat=='notinoc'])
> shapiro.test(weight[treat=='notinoc'])

	Shapiro-Wilk normality test

data:  weight[treat == "notinoc"]
W = 0.9778, p-value = 0.9735

> the normal probability plot appears in the plot window of RStudio *****************

> t.test(weight~treat)

	Welch Two Sample t-test

data:  weight by treat
t = -2.5483, df = 21.569, p-value = 0.01849
alternative hypothesis: true difference in means is not equal to 0
95 percent confidence interval:
 -8.1967826 -0.8365507
sample estimates:
 mean in group inocul mean in group notinoc
              8.97500              13.49167

> t.test(weight~treat, var.equal=TRUE)

	Two Sample t-test

data:  weight by treat
t = -2.5483, df = 22, p-value = 0.01832
alternative hypothesis: true difference in means is not equal to 0
95 percent confidence interval:
 -8.192517 -0.840816
sample estimates:
 mean in group inocul mean in group notinoc
              8.97500              13.49167

>
>