An article in Quality Engineering [“Designed Experiment to Stabilize Blood Glucose Levels” (1999–2000, Vol. 12, pp. 83–87)] reported on an experiment to minimize variations in blood glucose levels. The factors were: volume of juice intake before exercise (4 or 8 oz), amount of exercise on a Nordic Track cross-country skier (10 or 20 min), and delay between the time of juice intake (0 or 20 min) and the beginning of the exercise period. The experiment was blocked for time of day.

The data follow.

(a) What effects are confounded with blocks? Comment on any concerns with the confounding in this design.

(b) Analyze the data and draw conclusions.