Estimate the mean wage & proportion of white male/female professionals living in the north

Descriptive statistics for both male and female wages

##    vars   n mean   sd median trimmed  mad min   max range skew kurtosis  se
## X1    1 124 5.73 3.36   4.68    5.19 2.32 1.5 21.86 20.36 1.91     4.78 0.3

Descriptive statistics for female wages

##    vars  n mean  sd median trimmed  mad min   max range skew kurtosis   se
## X1    1 63  4.4 2.1   3.75     4.1 1.25 1.5 14.58 13.08 2.15     6.94 0.26

Descriptive statistics for male wages

##    vars  n mean   sd median trimmed  mad min   max range skew kurtosis   se
## X1    1 61 7.11 3.85   6.25    6.57 3.34   2 21.86 19.86 1.49     2.67 0.49
## data$female: Female
##       wage           female  
##  Min.   : 1.500   Female:63  
##  1st Qu.: 3.025   Male  : 0  
##  Median : 3.750              
##  Mean   : 4.396              
##  3rd Qu.: 5.150              
##  Max.   :14.580              
## ------------------------------------------------------------ 
## data$female: Male
##       wage           female  
##  Min.   : 2.000   Female: 0  
##  1st Qu.: 4.500   Male  :61  
##  Median : 6.250              
##  Mean   : 7.107              
##  3rd Qu.: 8.750              
##  Max.   :21.860

Observations for 63 females: - Minimal wage -> 1.5; - Maximal wage -> 14.58; - Wages mean -> 4.4; - Wages median -> 3.75; - Wages standard deviation -> 2.1

Observations for 61 males: - Minimal wage -> 2; - Maximal wage -> 21.86; - Wages mean -> 7.11; - Wages median -> 6.25; - Wages standard deviation -> 3.85

Boxplot with male and female wages

As it is displayed, male wages are significantly better. Male wages have a bigger: range, mean, median and lower standard deviation.

Male and female quantile-quantile plots are right skewed.

Female wages density function

Female wages are mostly distributed between 1.5 and 7.5

Female wages density function

Male wages are mostly distributed between 2 and 10

Calculated mean and confidence interval of a random sample of 20 female wages

## [1] 3.561031 4.598970

We are in 95% confident that the true female wages lies between the above two values.

Calculated mean and confidence interval of a random sample of 20 male wages

## [1] 6.404458 8.336543

We are in 95% confident that the true female wages lies between the above two values.

Estimated proportion interval in a random sample of 20 females who have wages lower than the population mean

## [1] 0.0430944 0.4100154

We are in 95% confident that the true proportion of females who have wages lower than the population mean lies between the above two values.

Calculated sample size needed to gain 0.1 error

## 
## sample.size.prop object: Sample size for proportion estimate
## With finite population correction: N=63, precision e=0.1 and expected proportion P=0.4996
## 
## Sample size needed: 39

The minimum sample size to gain 0.1 error is equal to 39.