Basic Statistics

Load Libraries

# if you haven't used a given package before, you'll need to download it first
# delete the "#" before the install function and run it to download
# re-insert the "#" before the install function so that the file will Knit later
# then run the library function calling that package

#install.packages("psych")
#install.packages("expss")

library(psych) # for the describe() command
library(expss) # for the cross_cases() command
## Loading required package: maditr
## 
## To get total summary skip 'by' argument: take_all(mtcars, mean)

##Import Data

# Import the "fakedata.csv" file

d2 <- read.csv("Data/projectdata.csv")


# Note: for the HW, you will import "projectdata.csv" that you created and exported in the Data Prep Lab

Univariate Plots: Histograms & Tables

Tables are used to visualize individual categorical variables. Histograms are used to visualize individual continuous variables.

# use tables to visualize categorical data
table(d2$income)
## 
##          1 low       2 middle         3 high rather not say 
##            876            879            534            854
table(d2$marriage5)
## 
##             are currently divorced from one another 
##                                                 735 
##                are currently married to one another 
##                                                2118 
##       never married each other and are not together 
##                                                 244 
## never married each other but are currently together 
##                                                  46
# use histograms to visualize continuous data
hist(d2$belong)

hist(d2$efficacy)

hist(d2$support)

hist(d2$stress)

Univariate Normality for Continuous Variables (individually)

describe(d2)
##             vars    n    mean     sd  median trimmed     mad min    max  range
## ResponseID*    1 3143 1572.00 907.45 1572.00 1572.00 1165.32 1.0 3143.0 3142.0
## income*        2 3143    2.43   1.16    2.00    2.42    1.48 1.0    4.0    3.0
## marriage5*     3 3143    1.87   0.60    2.00    1.83    0.00 1.0    4.0    3.0
## belong         4 3143    3.23   0.60    3.30    3.25    0.59 1.3    5.0    3.7
## efficacy       5 3143    3.13   0.45    3.10    3.13    0.44 1.1    4.0    2.9
## support        6 3143    5.54   1.13    5.75    5.66    0.99 0.0    7.0    7.0
## stress         7 3143    3.05   0.60    3.00    3.05    0.59 1.3    4.7    3.4
##              skew kurtosis    se
## ResponseID*  0.00    -1.20 16.19
## income*      0.15    -1.44  0.02
## marriage5*   0.46     1.47  0.01
## belong      -0.26    -0.12  0.01
## efficacy    -0.23     0.44  0.01
## support     -1.10     1.44  0.02
## stress       0.03    -0.16  0.01
## For the required write-up below, choose one of these options to paste and edit below based on your output.

## OPTION 1
# We analyzed the skew and kurtosis of our continuous variables and all were within the accepted range (-2/+2).

## OPTION 2
# We analyzed the skew and kurtosis of our continuous variables and (#) were within the accepted range (-2/+2). However, (#) variables (list variable name(s) here) were outside of the accepted range. For this analysis, we will use them anyway, but outside of this class this is bad practice.

We analyzed the skew and kurtosis of our continuous variables and all were within the accepted range (-2/+2).

Bivariate Plots

Crosstabs

Crosstabs are used to visualize combinations of two categorical variables.

cross_cases(d2, income, marriage5)
 marriage5 
 are currently divorced from one another   are currently married to one another   never married each other and are not together   never married each other but are currently together 
 income 
   1 low  298 458 105 15
   2 middle  199 613 55 12
   3 high  73 450 7 4
   rather not say  165 597 77 15
   #Total cases  735 2118 244 46 
# Note: for HW, replace the two lab variables with your project ones)

Scatterplots

Scatterplots are used to visualize combinations of two continuous variables.

plot(d2$support, d2$stress,
     main="Scatterplot of Social Support and Stress",
     xlab = " Social Support",
     ylab = "Stress")

plot(d2$belong, d2$stress, 
     main="Scatterplot of Need to Belong and Stress",
     xlab = "Need to Belong",
     ylab = "Stress")

# Note: for HW, you will choose to plot 2 combos of your 4 continuous variables, based on your hypotheses. You may repeat 1 variable to see its association with 2 others. You will need replace the variable names on the first line of the function as well as the 'main' (aka plot title), 'xlab' and 'ylab' lines to correctly label the graphs -- remember to use the actual variable names, not their scales, so someone reading your plots can understand them.

Boxplots

Boxplots are used to visualize combinations of one categorical and one continuous variable.

# ORDER MATTERS HERE: 'continuous variable' ~ 'categorical variable' 

boxplot(data=d2, stress~income,
        main="Boxplot of Yearly Income and Stress",
        xlab = "Yearly Income",
        ylab = "Stress")

boxplot(data=d2, belong~marriage5,
        main="Boxplot of Parents' Marital Status and Need to Belong",
        xlab = "Parents' Marital Status",
        ylab = "Need to Belong")

# Note: for HW, you will choose to plot 2 combos of any of your 4 continuous variables with either of your 2 categorical variables, based on your hypotheses. You may repeat 1 variable to see its association with others. Again, you will need replace the variable names on the first line of the function as well as the 'main' (aka plot title), 'xlab' and 'ylab' lines to correctly label the graphs -- remember to use the actual variable names, not their scales, so someone reading your plots can understand them.

We did it!!