## How would I use ANOVA to find the differences between means of three groups in a dataset

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I am trying to use ANOVA to find the differences between means of only 'group1', 'group2' and 'group5' in the below dataset.

tab_csv <- read.csv("data.csv", sep = "\t", header = TRUE) tab_csv label number 1 group1 120 2 group1 105 3 group1 105 4 group1 84 5 group1 32 6 group2 820 7 group2 922 8 group2 823 9 group2 945 10 group2 849 11 group3 1990 12 group3 29 13 group3 40 14 group3 21 15 group3 900 16 group4 220 17 group4 70 18 group4 109 19 group4 19 20 group4 18 21 group5 55 22 group5 40 23 group5 35 24 group5 30 25 group5 20 levels(tab_csv$label) [1] "group1" "group2" "group3" "group4" "group5"

I have started by trying this but I am not sure...

tab_csv$number[tab_csv$label == "group1"]) tab_csv$number[tab_csv$label == "group2"]) tab_csv$number[tab_csv$label == "group5"])

Could anyone please help?

This should be what you're looking for?

newdf <- df %>% filter(label %in% c("group1","group2","group5")) myaov <- aov(number ~ label, data = newdf)

**How would I use ANOVA to find the differences between means of ,** This should be what you're looking for? newdf <- df %>% filter(label %in% c(" group1","group2","group5")) myaov <- aov(number ~ label, data� One-Way Analysis of Variance (ANOVA) tells you if there are any statistical differences between the means of three or more independent groups.

You could do:

`groups<-c("group1","group2","group5")`

```
new.df<-tab_csv[which(levels(tab_csv$label)%in%groups,]
m1<-aov(new.df$number~new.df$label)
summary(m1)
```

Or you could pull from the original data.frame and run the following:

```
m2<-aov(tab_csv$number[which(tab_csv$label%in%groups)]~tab_csv$label[which(tab_csv$label%in%groups)])
summary(m2)
```

Probably prettier ways to do it...

**One-way ANOVA,** The one-way ANOVA is used to compare the means of more than two groups to find out if there is a difference in crop yields between the three groups. For a full walkthrough of this ANOVA example, see our guide to performing ANOVA in R. The sample dataset from our imaginary crop yield experiment� All ANOVAs are designed to test for differences among three or more groups. If you are only testing for a difference between two groups, use a t-test instead.

you can also use `subset`

to select your group in your dataframe:

# 1st - generating your dataframe group = c(rep("group1",5),rep("group2",5),rep("group3",5),rep("group4",5),rep("group5",5)) value = c(120,105,105,84,32,820,922,823,945,849,1990,29,40,21,900,220,70,109,19,18,55,40,35,30,20) df = data.frame(group = group,value = value) # performing anova > summary(aov(value ~ group, data = subset(df, group == "group1" | group =="group2" | group == "group5"))) Df Sum Sq Mean Sq F value Pr(>F) group 2 2189758 1094879 695.9 3.9e-13 *** Residuals 12 18880 1573 --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

**ANOVA Test: Definition, Types, Examples,** Basically, you're testing groups to see if there's a difference between them. A group of psychiatric patients are trying three different therapies: counseling, medication and A one way ANOVA is used to compare two means from two independent This means that the assumption has not been violated for this set of data. An ANOVA is used to determine whether or not there is a statistically significant difference between the means of three or more independent groups. If an ANOVA produces a p-value that is less than our significance level, we can use post hoc tests to find out which group means differ from one another.

**Comparing More Than Two Means: One-Way ANOVA,** Well, why not do a 0.05 significance test on pair of means? But if you test six 0.05 hypotheses on the same set of data, you're a false positive, finding a difference between two groups, pairs, α = 0.05, α = 0.01 Even with just three treatments, the� The ANOVA (analysis of variance) is a statistical test which makes a single, overall decision as to whether a significant difference is present among three or more sample means (Levin 484). An ANOVA is similar to a t-test. However, the ANOVA can also test multiple groups to see if they differ on one or more variables. The ANOVA can be used to

**One-Way ANOVA - SPSS Tutorials,** One-way ANOVA is used to test if the means of two or more groups are If you'd like to download the sample dataset to work through the examples, One-Factor ANOVA; One-Way Analysis of Variance; Between However, only the One-Way ANOVA can compare the means across three or more groups. There is a minor difference between T-test and AVOVA. Essentially, AVOVA will assist you in finding the mean for multiple samples. While the T-test will assist you with finding the mean for just two samples. Types of ANOVA. ANOVA has three types: One way analysis: When we are looking at multiple groups dependent on the one-factor variable. At

**Hypothesis Testing,** The test statistic must take into account the sample sizes, sample means and sample If one is examining the means observed among, say three groups, it might be analysis of variance indicates that there are differences among the groups). Distinguish between one and two factor analysis of variance tests; Identify the� An ANOVA (analysis of variance) is used to determine whether or not there is a statistically significant difference between the means of three or more groups. The most commonly used ANOVA tests in practice are the one-way ANOVA and the two-way ANOVA: One-way ANOVA: Used to test whether or not there is a statistically significant difference between the means of three or more groups when the groups can be split on one factor.

##### Comments

- When I try your code @HanselPalencia I get the error `object 'label' not found. Can you help? :)
- It's probably because your group column isn't called label? I just used your data frame and I wasn't able to reproduce your error. The above code is correct and should work if everything is where it's supposed to be.
- I was calling df instead of tab_csv my bad but thanks anyway :)
- I have ran your code again @HanselPalencia. However, now I am getting the error
`object 'label' not found`

. Can you please help? - What is your column name for your groups?
- Thanks so much @NoobR!
- Thanks so much @dc37!