Tabular Presentation of Data

1. Frequency table: It consists of three columns, the first column contains each of the events given in the data, and the second column contains the tally. The third column consists of the number of times an event occurs. (Frequency) for grouped data, the frequency table consists of class interval, tally, and frequency.
2. Cumulative frequency table: The cumulative frequence of a particular class is gotten by adding the frequency of the particular class to the frequencies of the classes before it. Therefore the cumulative frequency table is the table that shows the cumulative frequency of each of the classes.

Grouped Data

When the number of entries in a given data is large, there is need to group the data. In grouping any numerical data, the following statistical parameters are examined.

The following statical parameters are exemplified.

1. Class Interval: This is the number of group that a particular data is classified. Each interval contain equal unit of the data
2. Class limit: The last numbers in the class interval are called class limits. For instance in the interval 18-20, 18 and 20 are called the class limits, where 18 is the lower class limit and the 20 is the upper class limits.
3. Class mark: This is the mid-point of any class interval. It s got by adding the lower and the upper limit together and dividing the result by 2.

Example (1)

The record below shows the score obtained by some student in a maths test

12        15        20        25        30        20        30        15        12        12

15        12        25        12        20        12        20        12        15        25

12        15        12        15        12        15        20        12        15        25

30        25        15        30        20        15        25        30        15        12

12        15        12        15        12        30        20        20        12        15

Prepare a frequency table for the data above:

Example (2)

The following are the mark of 50m students of Danik Institute of management in diploma examination

65        70        60        47        51        55        59        63        68        63

47        53        72        53        67        52        64        70        57        56

73        56        48        51        58        63        65        62        49        64

53        59        63        50        48        72        67        56        61        64

66        52        49        62        71        58        53        69        63        59

Prepare a cumulative frequency table for the data using seven equal class interval

Solution

The class mark is 47

The highest mark is 73

Width of the class = 73 – 47 =3.71 _ 4units