TABLE 11-11
a Student Team in a Business Statistics Course

TABLE 11-11
A student team in a business statistics course designed an experiment to investigate whether the brand of bubblegum used affected the size of bubbles they could blow. To reduce the person-to-person variability, the students decided to use a randomized block design using themselves as blocks. Four brands of bubblegum were tested. A student chewed two pieces of a brand of gum and then blew a bubble, attempting to make it as big as possible. Another student measured the diameter of the bubble at its biggest point. The following table gives the diameters of the bubbles (in inches) for the 16 observations.
$$\begin{array}{l}\text { Brand of Bubblegum }\\\begin{array} { l c c c c } \hline \text { Student } & \text { A } & \text { B } & \text { C } & \text { D } \\\hline \text { Kyle } & 8.75 & 9.50 & 8.50 & 11.50 \\\text { Sarah } & 9.50 & 4.00 & 8.50 & 11.00 \\\text { Leigh } & 9.25 & 5.50 & 7.50 & 7.50 \\\text { Isaac } & 9.50 & 8.50 & 7.50 & 7.50 \\\hline\end{array}\end{array}$$
-Referring to Table 11-11, the randomized block F test is valid only if there is no interaction between the diameters of the 4 brands of bubble gums and the 4 ability of the students.