[R] ANOVA in R
p@u|john32 @end|ng |rom gm@||@com
Wed Oct 10 11:37:46 CEST 2018
We cannot read your message. Should post pure text, not html. Hm, my phone
now may post html, must try to stop. Your R code not legible. It seems to
be output? Lines all run together. I tried find articles you mention, but
"not found" resulted.
You should use aov() for fitting, then get post hoc comparisons.
In car package, Anova function will help. I may teach Anova soon, we'll see
if I have better answer then.
University of Kansas
On Wed, Oct 10, 2018, 1:14 AM Thanh Tran <masternhattt using gmail.com> wrote:
> Hi eveyone,
> I'm studying about variance (ANOVA) in R and have some questions to share.
> I read an article investigating the effect of factors (temperature, Asphalt
> content, Air voids, and sample thickness) on the hardness of asphalt
> concrete in the tensile test (abbreviated as Kic). Each condition was
> repeated four times (4 samples). In the paper, the authors used MINITAB to
> analyze Anova. The authors use "adjusted sums of squares" calculate the
> p-value I try to use ANOVA in R to analyze this data and get the result as
> shown in Figure 4. The results are different from the results in the
> article. Some papers say that in R, the default for ANOVA analysis is to
> use "sequential sums of squares" to calculate the p-value.
> So please help the following two questions: 1 / Introduction to code in R
> for anova analysis uses "adjusted sums of squares". The main part of the
> command in R / myself is as follows: > Tem = as.factor (temperature) > Ac =
> as.factor (AC) > Av = as.factor (AV) > Thick = as.factor (Thickness) >
> Twoway = lm (KIC ~ Tem + Ac + Av + Thick + Stamp + Ac + Stamp + Av + Stamp
> + Thick + Ac * Av + Ac * Thick + Av * Thick) > anova (twoway) 2/ When to
> use "sequential sums of squares" and when to use "adjusted sums of
> squares". Some papers recommend using the "oa.design
> function in R to check for "orthogonal" designs. If not, use "adjusted sums
> of squares". I am still vague about this command, so look forward to
> everyone's suggestion. If you could answer all two of my questions, I would
> be most grateful. Ps: I have added a CSV file and the paper for practicing
> R. http://www.mediafire.com/file/e5oe54p2c2wd4bc/Saha+research.csv
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