I'm planning a study on interaction techniques in virtual reality. That means I want to compare the performance of the participants on different interaction forms (e.g. selecting objects with a ray or by grabbing) in different scenarios (e.g. different distances and object sizes). My study design is rather complex and I'm not that familiar with data analysis so I hope you can help me with the following two questions:
I have multiple Independent variables. For simplification let's have a look on three of them. A is the interaction technique, B is the distance and C is the object size. Not all Interaction technique work for all distances. That means for some interaction techniques there will be missing data: \begin{array} {|r|r|}\hline & B_1 & B_2 & C_1 & C_2 \\ \hline A_1 & x & & x & x \\ \hline A_2 & x & x & x & x \\ \hline A_3 & x & x & x & x \\ \hline A_4 & x & & x & x \\ \hline ... & & & & \\ \hline \end{array} $X_1$ and $X_2$ indicate the different conditions of a variable $X$. After the study I want to analyse the data for $B_1$ and $B_2$ separately. If a technique does not support $B_2$ it will simple not considered in the analysis. Is this possible? I'm afraid that the two conditions are somehow connected. I think the cleanest way would be to do two studies investigate $B_1$ and $B_2$ separately but that would be more time consuming ...
I want to test 12 different interaction techniques. That's a lot and it is impossible to let all participants test all techniques. Therefore each participant will test 3 random interaction techniques. That means I have some kind of a mix of within-subject and between-subject design. Unfortunately there are no fixed groups because of the randomly assigned techniques. Therefore I cannot use a split plot ANOVA for example. Are there any other models I can use? Or is it possible to assume that each technique was used by a different person even if one person used multiple techniques? Then if would be possible to use a split plot ANOVA.