1.) What are the Cases in this data set? How Many cases are there in our sample?

Each cases represents data/information on a baby based on relations in both habits and practices of the mother. With their being a total of 1000 cases.

download.file("http://www.openintro.org/stat/data/nc.RData", destfile = "nc.RData")
load("nc.RData")

2.)

The plot highlights, that babies born to non-smoking moms have a higher birth weight at a overall degree, and contains more variety/variability yo their weight. But in general both groups share very similar weights, that are approximately normal.

summary(nc)
##       fage            mage            mature        weeks             premie   
##  Min.   :14.00   Min.   :13   mature mom :133   Min.   :20.00   full term:846  
##  1st Qu.:25.00   1st Qu.:22   younger mom:867   1st Qu.:37.00   premie   :152  
##  Median :30.00   Median :27                     Median :39.00   NA's     :  2  
##  Mean   :30.26   Mean   :27                     Mean   :38.33                  
##  3rd Qu.:35.00   3rd Qu.:32                     3rd Qu.:40.00                  
##  Max.   :55.00   Max.   :50                     Max.   :45.00                  
##  NA's   :171                                    NA's   :2                      
##      visits            marital        gained          weight      
##  Min.   : 0.0   married    :386   Min.   : 0.00   Min.   : 1.000  
##  1st Qu.:10.0   not married:613   1st Qu.:20.00   1st Qu.: 6.380  
##  Median :12.0   NA's       :  1   Median :30.00   Median : 7.310  
##  Mean   :12.1                     Mean   :30.33   Mean   : 7.101  
##  3rd Qu.:15.0                     3rd Qu.:38.00   3rd Qu.: 8.060  
##  Max.   :30.0                     Max.   :85.00   Max.   :11.750  
##  NA's   :9                        NA's   :27                      
##  lowbirthweight    gender          habit          whitemom  
##  low    :111    female:503   nonsmoker:873   not white:284  
##  not low:889    male  :497   smoker   :126   white    :714  
##                              NA's     :  1   NA's     :  2  
##                                                             
##                                                             
##                                                             
## 
boxplot(nc$weight[nc$habit == "nonsmoker"], nc$weight[nc$habit == "smoker"], 
        xlab = "Habit",
        ylab = "Qeight", 
        names = c ("nonsmoker", "smoker")
        ,col = "Lavender",
        ylim = c(0,14))

by(nc$weight, nc$habit, mean)
## nc$habit: nonsmoker
## [1] 7.144273
## ------------------------------------------------------------ 
## nc$habit: smoker
## [1] 6.82873

3.)

The condition’s based on the provided information due seem to be met, taking into consideration that both sample sizes are more than 30, the study/data being randomly sampled indicating independence.

by(nc$weight, nc$habit, length)
## nc$habit: nonsmoker
## [1] 873
## ------------------------------------------------------------ 
## nc$habit: smoker
## [1] 126

4.)

-The verge weights of babies born from smoking and non-smoking mothers aren’t different -The average weight of babies born from smoking and non-smoking mothers are diffident

5.)

inference(y = nc$weight, x =  nc$habit, est = "mean", type = "ci", null = 0,
          alternative = "twosided",
          method = "theoretical"
          ,order = c("smoker", "nonsmoker"))
## Response variable: numerical, Explanatory variable: categorical
## Difference between two means
## Summary statistics:
## n_smoker = 126, mean_smoker = 6.8287, sd_smoker = 1.3862
## n_nonsmoker = 873, mean_nonsmoker = 7.1443, sd_nonsmoker = 1.5187

## Observed difference between means (smoker-nonsmoker) = -0.3155
## 
## Standard error = 0.1338 
## 95 % Confidence interval = ( -0.5777 , -0.0534 )