getwd(
)
## [1] "C:/Users/Jerome/Documents/0000_Work_Files/0000_Coursera/Statistics_with_R_Specialization/Course_2_Inferential_Stats/Week3"
library(statsr)
## Warning: package 'statsr' was built under R version 4.0.3
library(dplyr)
## Warning: package 'dplyr' was built under R version 4.0.2
##
## Attaching package: 'dplyr'
## The following objects are masked from 'package:stats':
##
## filter, lag
## The following objects are masked from 'package:base':
##
## intersect, setdiff, setequal, union
library(ggplot2)
data(nc)
nc <- nc
write.csv (nc, file = "nc.csv", row.names = FALSE)
nc <- read.csv("nc.csv", header = TRUE)
str(nc)
## 'data.frame': 1000 obs. of 13 variables:
## $ fage : int NA NA 19 21 NA NA 18 17 NA 20 ...
## $ mage : int 13 14 15 15 15 15 15 15 16 16 ...
## $ mature : chr "younger mom" "younger mom" "younger mom" "younger mom" ...
## $ weeks : int 39 42 37 41 39 38 37 35 38 37 ...
## $ premie : chr "full term" "full term" "full term" "full term" ...
## $ visits : int 10 15 11 6 9 19 12 5 9 13 ...
## $ marital : chr "married" "married" "married" "married" ...
## $ gained : int 38 20 38 34 27 22 76 15 NA 52 ...
## $ weight : num 7.63 7.88 6.63 8 6.38 5.38 8.44 4.69 8.81 6.94 ...
## $ lowbirthweight: chr "not low" "not low" "not low" "not low" ...
## $ gender : chr "male" "male" "female" "male" ...
## $ habit : chr "nonsmoker" "nonsmoker" "nonsmoker" "nonsmoker" ...
## $ whitemom : chr "not white" "not white" "white" "white" ...
summary(nc$gained)
## Min. 1st Qu. Median Mean 3rd Qu. Max. NA's
## 0.00 20.00 30.00 30.33 38.00 85.00 27
p3 <- nc %>%
ggplot(aes(habit, weight, fill = habit)) +
ggtitle("Birth Weight by Smoke Status") +
xlab("Smoke Status") +
ylab("Birth WEight") +
geom_boxplot() +
scale_fill_discrete(name = "habit")
p3
nc %>%
group_by(habit) %>%
summarise(mean_weight = mean(weight))
## `summarise()` ungrouping output (override with `.groups` argument)
## # A tibble: 3 x 2
## habit mean_weight
## <chr> <dbl>
## 1 nonsmoker 7.14
## 2 smoker 6.83
## 3 <NA> 3.63
summary(nc$weight)
## Min. 1st Qu. Median Mean 3rd Qu. Max.
## 1.000 6.380 7.310 7.101 8.060 11.750
#install.packages("tables")
library("tables")
## Warning: package 'tables' was built under R version 4.0.5
tapply(nc$weight, nc$habit, summary)
## $nonsmoker
## Min. 1st Qu. Median Mean 3rd Qu. Max.
## 1.000 6.440 7.310 7.144 8.060 11.750
##
## $smoker
## Min. 1st Qu. Median Mean 3rd Qu. Max.
## 1.690 6.077 7.060 6.829 7.735 9.190
inference(y = weight, x = habit, data = nc, statistic = "mean", type = "ht", null = 0,
alternative = "twosided", method = "theoretical")
## Response variable: numerical
## Explanatory variable: categorical (2 levels)
## n_nonsmoker = 873, y_bar_nonsmoker = 7.1443, s_nonsmoker = 1.5187
## n_smoker = 126, y_bar_smoker = 6.8287, s_smoker = 1.3862
## H0: mu_nonsmoker = mu_smoker
## HA: mu_nonsmoker != mu_smoker
## t = 2.359, df = 125
## p_value = 0.0199
inference(y = weight, x = habit, data = nc, statistic = "mean", type = "ci",
method = "theoretical")
## Response variable: numerical, Explanatory variable: categorical (2 levels)
## n_nonsmoker = 873, y_bar_nonsmoker = 7.1443, s_nonsmoker = 1.5187
## n_smoker = 126, y_bar_smoker = 6.8287, s_smoker = 1.3862
## 95% CI (nonsmoker - smoker): (0.0508 , 0.5803)
inference(y = weight, x = habit, data = nc, statistic = "mean", type = "ci", conf_level = .99,
method = "theoretical")
## Response variable: numerical, Explanatory variable: categorical (2 levels)
## n_nonsmoker = 873, y_bar_nonsmoker = 7.1443, s_nonsmoker = 1.5187
## n_smoker = 126, y_bar_smoker = 6.8287, s_smoker = 1.3862
## 99% CI (nonsmoker - smoker): (-0.0343 , 0.6654)
inference(y = weeks, data = nc, statistic = "mean", type = "ci", conf_level = .99,
method = "theoretical")
## Single numerical variable
## n = 998, y-bar = 38.3347, s = 2.9316
## 99% CI: (38.0952 , 38.5742)
inference(y = weeks, data = nc, statistic = "mean", type = "ci", conf_level = .90,
method = "theoretical")
## Single numerical variable
## n = 998, y-bar = 38.3347, s = 2.9316
## 90% CI: (38.1819 , 38.4874)
table(nc$mature, nc$mage)
##
## 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
## mature mom 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
## younger mom 1 1 6 10 19 38 35 66 51 60 51 53 54 51 47 53 52 39 52 38 45 45
##
## 35 36 37 38 39 40 41 42 45 46 50
## mature mom 35 31 26 12 7 9 8 2 1 1 1
## younger mom 0 0 0 0 0 0 0 0 0 0 0