17.

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Page 116

		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.

		1— Left: Data Set #1

		The values x(n) seem to change randomly from one point in time to the next point in time.

		2— Right: Data Set #2

		The values x(n) seem to change randomly from one point in time to the next point in time.

 

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