[R-sig-eco] report out by t.test
I test differences between frequency of hits of exotic annual forbs in plots on two sites, Q and WD. > Q<-c(13,0,10,2,0,0,1,0,0,1,5) > WD<-c(0,0,1,0,0,0,0,0,0,0,1) > t.test(Q,WD) Welch Two Sample t-test data: Q and WD t = 1.9807, df = 10.158, p-value = 0.07533 alternative hypothesis: true difference in means is not equal to 0 95 percent confidence interval: -0.3342006 5.7887460 sample estimates: mean of x mean of y 2.9090909 0.1818182 The p-value is greater than 0.05, thus does not reach the 95% confidence level, yet the difference in means is reported as not equal to 0. Am I encountering a one-sided versus two sided comparison that I don't understand, or is ther another explanation? Mike Marsh ___ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
[R-sig-eco] Plot question
Dear R friends, I have to produce a plot like the one attached on the file. The idea is to plot the time spent for a spider over several different prey, the spiders were repreated in the different trials. If any of you knows how to perform this plot or have any source which explains how to do it, I would really appreciate it. Thanks in advance. Plot : http://imgur.com/u1FNmwn spider preytime 1 cockroach 136 1 ant 128 1 termite 115 1 fly 145 1 isopod 115 2 cockroach 187 2 ant 142 2 termite 114 2 fly 115 2 isopod 123 3 cockroach 111 3 ant 121 3 termite 113 3 fly 115 3 isopod 117 4 cockroach 142 4 ant 132 4 termite 156 4 fly 142 4 isopod 113 5 cockroach 115 5 ant 121 5 termite 217 5 fly 213 5 isopod 112 ___ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
Re: [R-sig-eco] Plot question
Garcia,
Just use ggplot2, here is some code to illustrate:
--
library(ggplot2)
#Create some dummy data with x, y and category columns
mysample <- function(category)
data.frame(x=c(1:10),y=c(10:1)*(1+0.25*runif(10)),Category=category)
dfA = mysample("A")
dfB = mysample("B")
dfC = mysample("C")
df = rbind(dfA,dfB,dfC)
#and plot
ggplot(data=df,aes(x,y,color=Category)) + geom_point() + geom_path() +
labs(x="xaxis",y="yaxix",title="The title")
-
Regards,
Nicholas Hamilton
UNSW School of Materials Science and Engineering
www.ggtern.com
From: r-sig-ecology-boun...@r-project.org [r-sig-ecology-boun...@r-project.org]
on behalf of Luis Fernando García [luysgar...@gmail.com]
Sent: Monday, March 24, 2014 11:32 AM
To: r-sig-ecology@r-project.org
Subject: [R-sig-eco] Plot question
Dear R friends,
I have to produce a plot like the one attached on the file. The idea is to
plot the time spent for a spider over several different prey, the spiders
were repreated in the different trials. If any of you knows how to perform
this plot or have any source which explains how to do it, I would really
appreciate it.
Thanks in advance.
Plot : http://imgur.com/u1FNmwn
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Re: [R-sig-eco] Plot question
Hi Luis,
You can try this:
# enter data
spider <- c(1,1,1,1,1,2,2,2,2,2,3,3,3,3,3,4,4,4,4,4,5,5,5,5,5)
prey <-
c("cockroach","ant","termite","fly","isopod","cockroach","ant","termite","fly","isopod","cockroach","ant","termite","fly","isopod","cockroach","ant","termite","fly","isopod","cockroach","ant","termite","fly","isopod")
time <-
c(136,128,115,145,115,187,142,114,115,123,111,121,113,115,117,142,132,156,142,113,115,121,217,213,112)
# turn into a dataframe
dat <- data.frame(spider=spider, prey=prey, time=time)
# set and reorder factors
dat$spider <- factor(dat$spider)
dat$prey = factor(dat$prey,levels(dat$prey)[c(3,5,2,1,4)])
# check data
str(dat)
head(dat)
# import plotting library and make plot
library(ggplot2)
p = ggplot(data=dat, aes(prey, time, group = spider, colour= spider))
p + geom_line() + geom_point(shape=1, size=4) + theme_bw()
Best,
Tim
On Sun, Mar 23, 2014 at 8:08 PM, Nicholas Hamilton <
n.hamil...@student.unsw.edu.au> wrote:
> Garcia,
>
> Just use ggplot2, here is some code to illustrate:
>
> --
>
> library(ggplot2)
>
> #Create some dummy data with x, y and category columns
> mysample <- function(category)
> data.frame(x=c(1:10),y=c(10:1)*(1+0.25*runif(10)),Category=category)
> dfA = mysample("A")
> dfB = mysample("B")
> dfC = mysample("C")
> df = rbind(dfA,dfB,dfC)
>
> #and plot
> ggplot(data=df,aes(x,y,color=Category)) + geom_point() + geom_path() +
> labs(x="xaxis",y="yaxix",title="The title")
>
> -
> Regards,
>
> Nicholas Hamilton
> UNSW School of Materials Science and Engineering
> www.ggtern.com
>
>
>
> From: r-sig-ecology-boun...@r-project.org [
> r-sig-ecology-boun...@r-project.org] on behalf of Luis Fernando García [
> luysgar...@gmail.com]
> Sent: Monday, March 24, 2014 11:32 AM
> To: r-sig-ecology@r-project.org
> Subject: [R-sig-eco] Plot question
>
> Dear R friends,
>
> I have to produce a plot like the one attached on the file. The idea is to
> plot the time spent for a spider over several different prey, the spiders
> were repreated in the different trials. If any of you knows how to perform
> this plot or have any source which explains how to do it, I would really
> appreciate it.
>
> Thanks in advance.
>
>
> Plot : http://imgur.com/u1FNmwn
>
> ___
> R-sig-ecology mailing list
> R-sig-ecology@r-project.org
> https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
>
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Re: [R-sig-eco] report out by t.test
The sentence "alternative hypothesis: true difference in means is not equal to 0" is stating what the alternative hypothesis is and not that your particular difference in means is significantly different from zero. That sentence would appear (when you have a two-tailed test) no matter what the P-value might be. Try t.test(Q,WD) t.test(Q,WD,alternative="two.sided") # Default t.test(Q,WD,alternative="less") t.test(Q,WD,alternative="greater") Jim Jim Baldwin USDA Forest Service -Original Message- From: r-sig-ecology-boun...@r-project.org [mailto:r-sig-ecology-boun...@r-project.org] On Behalf Of Michael Marsh Sent: Sunday, March 23, 2014 2:22 PM To: r-sig-ecology@r-project.org Subject: [R-sig-eco] report out by t.test I test differences between frequency of hits of exotic annual forbs in plots on two sites, Q and WD. > Q<-c(13,0,10,2,0,0,1,0,0,1,5) > WD<-c(0,0,1,0,0,0,0,0,0,0,1) > t.test(Q,WD) Welch Two Sample t-test data: Q and WD t = 1.9807, df = 10.158, p-value = 0.07533 alternative hypothesis: true difference in means is not equal to 0 95 percent confidence interval: -0.3342006 5.7887460 sample estimates: mean of x mean of y 2.9090909 0.1818182 The p-value is greater than 0.05, thus does not reach the 95% confidence level, yet the difference in means is reported as not equal to 0. Am I encountering a one-sided versus two sided comparison that I don't understand, or is ther another explanation? Mike Marsh ___ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology This electronic message contains information generated by the USDA solely for the intended recipients. Any unauthorized interception of this message or the use or disclosure of the information it contains may violate the law and subject the violator to civil or criminal penalties. If you believe you have received this message in error, please notify the sender and delete the email immediately. ___ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
