source: Doc/Requirements/scales.tex @ 532

The system needs to support different ways in which as question can be asked. This section will
describe the various ways we have identified. We also note which measurement scale belongs to
such a data source, to explain what statistical operations can be performed on resulting
datasets. 

\subsection{Question types}
        \subsubsection{Free response}
                This is a question for which the respondent can answer anything, given certain
                restrictions. It can be a specific datatype (like integer or text) and have specific
                restrictions (like 0 $\leq$ x $\leq$ 100, or text length $\leq$ 100). 
                \begin{figure}[h]
                        \begin{center}
                                \caption{An example of a free response question.}
                                \includegraphics{free_response.png}
                        \end{center}    
                \end{figure}    

        \subsubsection{Multiple choice, single answer}
                This is a multiple choice question with mutually exclusive answers. The resulting data
                type can differ per question.
                \begin{figure}[h]
                        \begin{center}
                                \caption{An example of a multiple choice, single answer question}
                                \includegraphics[scale=.5]{mpchoice_single.png}
                        \end{center}
                \end{figure}            
        
        \subsubsection{Multiple choice, multiple answer}
                This is a multiple choice question with non-mutual exclusive answers. The resulting
                data type can differ per question.
                \begin{figure}[h]
                        \begin{center}
                                \caption{An example of a multiple choice, multiple answer question}
                                \includegraphics[scale=.5]{mpchoice_multi.png}
                        \end{center}
                \end{figure}
        
        \subsubsection{Boolean questions}
                Boolean questions can be used to ask simple questions in the form of Yes/No,
                Agree/Disagree, True/False, etcetera. This is a more specific version of the multiple
                choice, single answer question. It gets its own category because it belongs to a
                different scale.
                \begin{figure}[h]
                        \begin{center}
                                \caption{An example of a boolean question.}
                                \includegraphics[scale=.5]{boolean_question.png}
                        \end{center}
                \end{figure}

        \subsubsection{Choice grids, single answer}
                Choice grids are used to answer questions or grade statements based on a custom-made
                scale. This scale also determines the measurement type scale. This type is defined by
                the attribute that each row is similar to a multiple choice, single answer question.
                \begin{figure}[h!]
                        \begin{center}
                                \caption{An example of a choice grid, single answer}
                                \includegraphics[scale=.5]{choice_grid_single.png}
                        \end{center}
                \end{figure}    
        \subsubsection{Choice grids, multiple answer}
                Choice grids are used to answer questions or grade statements based on a custom-made
                scale. This scale also determines the measurement type scale. This type is defined by
                the attribute that each row is similar to a multiple choice, multiple answer question.
                \begin{figure}[h!]
                        \begin{center}
                                \caption{An example of a choice grid, multiple answer}
                                \includegraphics[scale=.5]{choice_grid_multi.png}
                        \end{center}
                \end{figure}

\subsection{Game Data}
        Game data will obviously differ greatly depending on the game that will be played. This is
        why this has to be specified on a per-game basis. 
        
\subsection{Measurement scales}
        Different levels of measurement allow for different types of permissible operations on a
        dataset. Seeing as the questions and game results can be seen as statistical data, we will
        have to differ between them based on their scale type.

        Information about scale types can be found on 
        Wikipedia\footnote{http://en.wikipedia.org/wiki/Level\_of\_measurement} or in figure 
        \ref{f:levels}. 

\begin{figure}[h]
        \label{f:levels}
        \caption{The differences between levels of measurement.}
        \includegraphics[width=\textwidth]{measurementlevels.png}
\end{figure}

        Every type of question and every type of game data belongs to one of these four scales,
        which have to be specified by the Survey's creator. By adding the information of
        measurement scale, we can support the various statistical computations that are allowed on
        every data type.