In an Experiment Designed to Study the Effects of Illumination

Essay

In an experiment designed to study the effects of illumination level on task performance, subjects were required to insert a fine-tipped probe into the eyeholes of ten needles in rapid succession both for a low light level with black background and a higher level with a white background. Each data value is the time (sec) required to complete the task.
Subject $$\begin{array} { l | c c c c c c c c c } \hline & \mathbf { 1 } & \mathbf { 2 } & \mathbf { 3 } & \mathbf { 4 } & \mathbf { 5 } & \mathbf { 6 } & \mathbf { 7 } & \mathbf { 8 } & \mathbf { 9 } \\\hline \text { Black } & 25.01 & 41.05 & 27.47 & 25.74 & 24.96 & 28.84 & 25.85 & 20.89 & 32.05 \\\text { White } & 16.61 & 24.98 & 24.59 & 19.68 & 16.07 & 20.84 & 18.23 & 19.50 & 22.96 \\\hline\end{array}$$ Does the data indicate that the higher level of illumination yields a decrease of more than 5 sec in
true average task completion time? Test the appropriate hypotheses using the P-value approach.