The interval variational series represents the table consisting of two columns or lines. In the first the interval of sign which variation is considered, is specified in the second – number of the units of population getting to this interval (frequencies).
Instruction
1. To construct an interval variational series, first of all it is necessary to choose optimum number of intervals and to establish length of each of them. At the same time consider that length of an interval has to be a constant as in the analysis of a variational series compare frequencies from different groups. The optimum number of groups needs to be chosen so that to reflect a variety of signs of set and at the same time their natural distribution and also to exclude distortion of set accidental fluctuations of frequencies. Consider that if groups will be not enough, the regularity of distribution will not be visible and if, on the contrary, there is too much – accidental jumps of units of population will distort a number of distribution.
2. For definition of number of groups in a variational series use a formula Sterzhdesa: h = 1 + 3.322 x ln(n), gdeh – number of groups in a variational series; n – set number. If the received value is fractional, then for value of size of a step of an interval, take any next integer.
3. Then determine interval size: i = (Xmax – Xmin) / h, gdekhmax – the maximum value of sign in total; Xmin is the minimum value of sign in total.
4. Further fill interval borders. They can be specified in different ways: the upper bound of the previous interval can repeat the lower bound of the following (5-10, 10-15, 15-20) or not repeat (5-10, 10.1-15, 15.1-20). The following value is accepted to the beginning of the first interval of A0: A0 = Xmin – i/2, gdei – interval length. The Aj value representing the upper bound of j-go of an interval and the beginning (j+1) - go an interval is accepted to the end of j-go of an interval: Aj = A(j-1) + i. Creation of a scale of intervals continues until the size Aj satisfies to Aj ratio