HP 48gII hp 48gII_user's manual_English_E_HDPMSG48E67_V2.pdf - Page 576

Coefficient of variation The coefficient of variation of a sample combines the mean, a measure of central tendency, with the standard deviation, a measure of spreading, and is defined, as a percentage, by: Vx = (sx/x)100. Sample vs. population The pre-programmed functions for single-variable statistics used above can be applied to a finite population by selecting the Type: Population in the SINGLE-VARIABLE STATISTICS screen. The main difference is in the values of the variance and standard deviation which are calculated using n in the denominator of the variance, rather than (n-1). Example 3 -- If you were to repeat the exercise in Example 1 of this section, using Population rather than Sample as the Type, you will get the same values for the mean, total, maximum, and minimum. The variance and standard deviation, however, will be given by: Variance: 0.852, Std Dev: 0.923. Obtaining frequency distributions The application 2. Frequencies.. in the STAT menu can be used to obtain frequency distributions for a set of data. Again, the data must be present in the form of a column vector stored in variable ΣDAT. To get started, press ,Ù˜ @@@OK@@@. The resulting input form contains the following fields: ΣDAT: Col: X-Min: Bin Count: Bin Width: the matrix containing the data of interest. the column of ΣDAT that is under scrutiny. the minimum class boundary (default = -6.5). the number of classes(default = 13). the uniform width of each class (default = 1). Definitions To understand the meaning of these parameters we present the following definitions: Given a set of n data values: {x1, x2, ..., xn} listed in no particular order, it is often required to group these data into a series of classes by counting the frequency or number of values corresponding to each class. (Note: the calculators refers to classes as bins). Page 18-5