FRAME 34.

From this example, it can be seen that to reach valid conclusions it is important to measure

how data are dispersed around the measure of central tendency.

Dispersion is important, not merely as a supplement to the mean, but also as a significant

item in itself. The performance of a student is judged not only by his average but also by his

consistency. When a measure of central tendency and a measure of dispersion have been

computed for a series, generally the two most important characteristics have been summarized.

The first measure of dispersion that we will examine is the range. The range is the difference

between the highest and lowest values in a group of observations. In the example above, the

range of Group A is 10,000 -1,000 9,000, and the range of Group B is 4,500 -2,500 = 2,000. This

quickly illustrates that Group B's wages vary much less than Group A's wages.

FRAME 35.

Generally it is desirable to express the range in terms of the upper and lower limits; thus, we

would say A's range is
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,000 to ,000 and B's is ,500 to ,500. This gives the reader an

idea of the general location of the data.

Although it has the merit of being simple, the range is a rather unsatisfactory measure

because it is determined only by the two extreme values in a group of observations, the high and

the low. Since these two figures are only "boundaries" of the rest of the data, they are insensitive

to the behavior or location of figures between them. The range should be used only in cases

where a quick, cursory look at the data is desired.

QUESTION:

Find the range of the following costs:

00

2750

2400

3800

4500

3100

2800

Range = _________________