| | | | | | 2.1.1— Two Sets of Data That Look Alike | | | | | | | | | Each graph on the facing page consists of a set of data. Each data value is measured at one instant in time. These instants in time are separated by constant intervals in time. The n-th measurement is denoted by x(n). The values measured are shown as dots. Consecutive values have been connected by straight lines. | | | | | | | | | Both sets of data also have the same statistical properties. That is, both sets of data have the same average, variance, and power spectrum. | | | | | | | | | Each graph does not have the same values of x(n). However, the pattern of variation in each graph looks similar. The values of x(n) seem to vary in a random way with n. Therefore, it seems reasonable to believe that both sets of data were generated by an inherently random mechanism. | | | | | | | | | The values x(n) seem to change randomly from one point in time to the next point in time. | | | | | | | | | The values x(n) seem to change randomly from one point in time to the next point in time. | | | | |