Weekly Assignment 4

Simulate a brand new data frame (the type of data is up to you) and conduct a statistical analysis in R using 2 variables. Create a basic ggplot that goes with the analysis.

# glimpse(iris)
# we are making a box plot that will compared species to sepal length
flwr<-data.frame(iris$Species, iris$Sepal.Length) # create a df with these variables from the iris data set

I’m going to do an ANOVA Test to test if there is significance between these two variables:
- ANOVA and t-tests are used for statistical analysis when x is a categorical variable and y is a continuous variable. Box and bar plots are the preferred plots for these analyses.

ANOV<-aov(iris.Sepal.Length ~ iris.Species, data=flwr) # use iris data, aov requires data to be formatted y~x
summary(ANOV) # summary table of aov

##               Df Sum Sq Mean Sq F value Pr(>F)    
## iris.Species   2  63.21  31.606   119.3 <2e-16 ***
## Residuals    147  38.96   0.265                   
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

pvalue_func<-function(data=ANOV){ # used this function I created in Weekly Assignment 2
  p<-summary(ANOV)[[1]][["Pr(>F)"]][1] # extract the first element in the first compartment named "Pr(>F)" (the p value)
  return(p)
}

pvalue_func(data=ANOV)

## [1] 1.669669e-31

Now I’m going to create a box plot:

library(viridis)

## Loading required package: viridisLite

library(ggplot2)
cols<-viridis(3, option = "plasma") # takes 3 hex color codes from the viridis color packages. # also plasma, turbo, viridis. # have to give it the same number of colors as you have groups

flwrbox<-ggplot(data=flwr, aes(x=iris.Species,y=iris.Sepal.Length, fill=iris.Species)) + # create a ggplot using flwr data where x=species, y=sepal length, and the boxes are filled based on species
  geom_boxplot() + # create a box plot
  scale_fill_manual(values=cols, name = "Species") + # name the legend Species
  labs(title="Difference in Sepal Length Among Species",
       subtitle="Abby Griffin BIOL 1007A",
            x="Species",
            y="Sepal Length") + # naming title/subtitle/x/y axes
  theme_classic() + # remove background and gridlines
  theme(plot.title = element_text(color = "black"),
        plot.subtitle = element_text (color = "grey60")
        ) + # change color of title/subtitle
  annotate("text", x = 2, y = 7.5, label = "p=1.669669e-31")
print(flwrbox)

Weekly Assignment 4

Abigail Griffin

2023-01-31