To determine the photo-copying cost difference between the two printing orientations ( portrait and landscape), a study was carried out. The type of font (Arial, Calibri, and Times New Roman) that will minimize the cost is also of interest. Eight 3 page word documents were chosen out of which four were to be printed in portrait format and the other four were to be printed in landscape. The 3 pages in each document were randomly assigned to the three fonts such such that the text on a given page was typed using the assigned font. Using special measuring devices, the ink and the time required for the printing of each page was then recorded. The randomization design in this study is a?