When a number of distribution is already given, it is possible to start its research at once. But in some tasks as basic data numbers are presented just (the weight, the sum, quantity – any values of parameter or sign). In that case to begin the analysis, at first it is necessary to construct an interval row.
It is required to you
- - values of parameter.
Instruction
1. If values of parameter change eventually, use as intervals periods of time, for example, hour, day, month, year. When choosing the minimum interval consider quantity and variability of data, try that a number distributionsof it appeared the most informative and at the same time compact. For example, if you were given data on months within two years, breakdown for years will not be able to tell about anything, and use as an interval in certain cases will lead month to washing out of data. Breakdown by quarters will become an optimal solution at the same time.
2. If time for drawing up sample does not matter, create interval intervals depending on values. For this purpose estimate variability of data, their maximum and minimum value and choose interval size. It is possible to use such method: subtract from the maximum value minimum and divide the received difference into desirable quantity of intervals. Then establish borders, of course, better if it are integers. For example, you are given number 32, 33, 35, 38, 45, 47, 48, 50, 58, 59, 63. After calculations you receive (63-32)/5=6.2. Round the interval size to 7. Thus, you receive intervals: (32-39), (40-47), (48-55), (56-63).
3. Pay attention, it is the best of all to do borders of intervals not crossed, that is begin the following interval not with the same number, and from bigger on unit. Thanks to it you will be able to avoid disagreements and misunderstanding.
4. After you distribute all intervals, count amount of values in each of them. Write down the received results in the table where in one line borders will be specified, in another – amount of the values lying in borders of this interval. In the example reviewed above the calculation of amount of results will look so: the interval (32-39) includes values 32, 33, 35, 38 – only 4 values. Means, under this interval specify number 4 in the first cell of the table. In the same way calculate values for the following intervals: (40-47) – 2, (48-55) – 2, (56-63) – 3.