Jacob Elrod
Load in and rename Dataset, make sex a factor for convienence
library(readxl)
df <- read_excel("~/Copy of Head morphology.xlsx")
str(df)## tibble [358 x 8] (S3: tbl_df/tbl/data.frame)
## $ SPECIES : chr [1:358] "R. grahamii" "R. grahamii" "R. grahamii" "R. grahamii" ...
## $ SVL_(cm) : num [1:358] 26 43 37.5 62.5 19 19 19 20 19.5 18 ...
## $ SEX : chr [1:358] "male" "male" "female" "male" ...
## $ TEETH_NUMBER : num [1:358] 24 NA 24 26 24 23 NA NA 27 NA ...
## $ head_width_(mm) : num [1:358] 6.5 6.8 6.4 11.3 5.8 5.3 5.3 5.2 4.9 5 ...
## $ head_length_(mm): num [1:358] 10.3 13.8 11.9 14.5 10 9.8 10 9.8 10 9.4 ...
## $ jaw_length_(mm) : num [1:358] 11 15 12.4 15 10 10.2 9.8 9 9 9.2 ...
## $ GAPE_INDEX : num [1:358] 56.8 73.2 62 83.4 51.4 ...
df$SEX<- as.factor(df$SEX) Take dataset, omit NAs, group by sex and species, take the mean of teeth number by sex and species
df_sum<-df%>% na.omit() %>% group_by(SEX ,SPECIES) %>% summarize(mean_teeth = mean(TEETH_NUMBER))## `summarise()` has grouped output by 'SEX'. You can override using the `.groups` argument.
df_sum## # A tibble: 10 x 3
## # Groups: SEX [2]
## SEX SPECIES mean_teeth
## <fct> <chr> <dbl>
## 1 female R. grahamii 24.5
## 2 female R. septemvittata 24.3
## 3 female T. eques 36.8
## 4 female T. mel eat crayfish 34.4
## 5 female T. mel No eat crayfish 33.2
## 6 male R. grahamii 24.5
## 7 male R. septemvittata 24.7
## 8 male T. eques 37.3
## 9 male T. mel eat crayfish 34.6
## 10 male T. mel No eat crayfish 31.9
First a density plot to show distributions of teeth number, to see if data is normal just in case we eventually want to do statistical tests.
ggplot(df, aes(x = TEETH_NUMBER, fill = factor(SPECIES), )) + geom_density(alpha = .5)## Warning: Removed 26 rows containing non-finite values (stat_density).
Next, a point plot using the average of each species, colored by sex.
ggplot(df_sum, aes(x= SPECIES, y= mean_teeth, col = SEX))+geom_point()
By the analysis and visualization, we can see that the overall mean and median of the number of teeth in snakes doesn’t seem to vary much by sex of the snake(except for potentially T.Mel no eat crayfish), but clearly differs by species. This could be further proven by a statistic test that compares means such as a t test for the male and female, and perhaps and ANOVA for the species.