measurement-swirl.rnw

\section{Swirl Review Questions}
  \subsection{Lesson 1}
  \begin{enumerate}             
    \item What are some reasons for non-response in surveys?
    \begin{enumerate}
      \item respondents refuse to answer
      \item respondents don't know the answer
      \item both of these
    \end{enumerate}
    \if1\solutions
    \noindent{\bf Solution:}
    <<eval=FALSE>>=
    both of these
    @
    \fi
    \item Listwise deletion will delete an entire observation if \_\_\_\_\_\_\_\_.
    \begin{enumerate}
      \item at least one of its variables has a missing value
      \item if all of its variables are missing
      \item if none of its variables are missing
    \end{enumerate}
    \if1\solutions
    \noindent{\bf Solution:}
    <<eval=FALSE>>=
    at least one of its variables has a missing value
    @
    \fi
    \item Histograms create \_\_\_\_\_\_\_\_\_\_ along the variable of interest.
    \begin{enumerate}
      \item intervals
      \item bins
      \item both are correct
    \end{enumerate}
    \if1\solutions
    \noindent{\bf Solution:}
    <<eval=FALSE>>=
    both are correct
    @
    \fi
    \item When printing and saving graphs use \_\_\_\_\_\_\_\_\_\_ to open a pdf device and \_\_\_\_\_\_\_\_\_\_ to close the device.
    \begin{enumerate}
      \item \rfun{pdf()} and \rfun{dev.off()}
      \item \rfun{pdf.open()} and \rfun{dev.close()}
      \item \rfun{pdf.on()} and \rfun{dev()}
    \end{enumerate}
    \if1\solutions
    \noindent{\bf Solution:}
    <<eval=FALSE>>=
    pdf() and dev.off()
    @
    \fi
    \item 'Without replacement' in a survey means each individual is interviewed \_\_\_\_\_\_\_\_\_\_.
    \begin{enumerate}
      \item once
      \item many times
      \item either of these
    \end{enumerate}
    \if1\solutions
    \noindent{\bf Solution:}
    <<eval=FALSE>>=
    once
    @
    \fi
    \item How do we summarize the Afghan data?
    \if1\solutions
    \newline\newline \noindent{\bf Solution:}
    <<eval=FALSE>>=
    summary(afghan)
    @
    \fi
    \item Looking at the summary data, which of these variables has missing values?
    \begin{enumerate}
      \item \rexpr{violent.exp.ISAF}
      \item \rexpr{employed}
      \item \rexpr{age}
    \end{enumerate}
    \if1\solutions
    \noindent{\bf Solution:}
    <<eval=FALSE>>=
    violent.exp.ISAF
    @
    \fi
    \item Looking at the summary statistics, what is the mean number of years of education among the respondents?
    \if1\solutions
    \newline\newline \noindent{\bf Solution:}
    <<eval=FALSE>>=
    '4'
    @
    \fi
    \item Make a table of proportions in each province by employment status.
    \if1\solutions
    \newline\newline \noindent{\bf Solution:}
    <<eval=FALSE>>=
    prop.table(table(afghan$province, afghan$employed))
    @
    \fi
    \item How would you count the total number of missing elements of \rexpr{violent.exp.taliban}?
    \if1\solutions
    \newline\newline \noindent{\bf Solution:}
    <<eval=FALSE>>=
    sum(is.na(afghan$violent.exp.taliban))
    @
    \fi
  \end{enumerate}
  \subsection{Lesson 2}
  \begin{enumerate}
    \item In section 3.6, what kind of plot are we using to visualize ideological differences between Democrats and Republicans?
    \begin{enumerate}
      \item scatterplot
      \item bar plot
      \item histogram
    \end{enumerate}
    \if1\solutions
    \noindent{\bf Solution:}
    <<eval=FALSE>>=
    scatterplot
    @
    \fi
    \item True or False: Political polarization describes the phenomenon where the ideological centers of two political parties diverge over time.
    \begin{enumerate}
      \item True
      \item False
    \end{enumerate}
    \if1\solutions
    \noindent{\bf Solution:}
    <<eval=FALSE>>=
    'True'
    @
    \fi
    \item What angle is the Lorenz curve if everyone earns exactly the same income?
    \begin{enumerate}
      \item 30 degrees
      \item 45 degrees
      \item 90 degrees
    \end{enumerate}
    \if1\solutions
    \noindent{\bf Solution:}
    <<eval=FALSE>>=
    45 degrees
    @
    \fi
    \item To estimate the correlation between two variables x and y, we need to know the mean of each as well as the \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_.
    \begin{enumerate}
      \item maximum
      \item standard deviation
      \item length
    \end{enumerate}
    \if1\solutions
    \noindent{\bf Solution:}
    <<eval=FALSE>>=
    standard deviation
    @
    \fi
    \item In the \rfun{kmeans()} function which option is used to define the number of clusters?
    \begin{enumerate}
      \item centers
      \item groups
      \item iterations
    \end{enumerate}
    \if1\solutions
    \noindent{\bf Solution:}
    <<eval=FALSE>>=
    centers
    @
    \fi
    \item Use \rexpr{\rfun{matrix()}} to create a matrix of 2 rows by 5 columns filled by row with the numbers 1 through 10. Assign this matrix to an object called \rexpr{x}.
    \if1\solutions
    \newline\newline \noindent{\bf Solution:}
    <<eval=FALSE>>=
    x <- matrix(1:10, nrow = 2, ncol = 5, byrow = TRUE)
    @
    \fi
    \item Take the row means of this matrix
    \if1\solutions
    \newline\newline \noindent{\bf Solution:}
    <<eval=FALSE>>=
    rowMeans(x)
    @
    \fi
    \item A list, \rexpr{z}, has been included in this lesson. Call the list object to see what it looks like.
    \if1\solutions
    \newline\newline \noindent{\bf Solution:}
    <<eval=FALSE>>=
    z
    @
    \fi
    \item Call the first element of the list using brackets and the number 1.
    \if1\solutions
    \newline\newline \noindent{\bf Solution:}
    <<eval=FALSE>>=
    z[[1]]
    @
    \fi
    \item Call the third element of the list using brackets and the name of the third element.
    \if1\solutions
    \newline\newline \noindent{\bf Solution:}
    <<eval=FALSE>>=
    z[["z3"]]
    @
    \fi
  \end{enumerate}