Following are the steps involved in the construction of frequency distribution

What are the difference between Diagrams and Graphs?

At a time we are interested in knowing how many workers of a factory earn less than Rs. 700 per month or how many workers earn more than Rs. 1,000 per month, percentage of students who have failed etc.

Frequency curve is obtained by joining the points of frequency polygon by a freehand smoothed curve.

Frequency polygon is a closed figure got by joining the Middle points of the top of rectangles of histograms.

It consists of a number of rectangles, those are vertically adjacent. Class intervals are taken on X-axis and frequencies on Y-axis. Rectangles are formed of the height proportionate to their frequencies.

A graph refers to the plotting of different valves of the variables on a graph paper which gives the movement or a change in the variable over a period of time.

Although tabulation is very good technique to present the data, but diagrams are an advanced technique to represent data.

What are the Merits and Demerits of Rank Difference Co-efficient of Correlation?

What are the Merits and Demerits of Scatter Diagram?

The measures of Central Tendency and Dispersion are used to compare two or more series. But it is not the comparison that is always wanted.

The objects of Descriptive Statistics are mainly - condensation by frequency distribution, and description of the frequency distribution by suitable statistical measures.

It is the form of a curve which is derived from the cumulative percentage of the given variables. This curve was given by Dr. Max O. Lorenz a popular Economic- Statistician. He studied distribution of Wealth and Income with its help.

The idea of Standard Deviation was first presented by Karl Pearson in 1893. This measure is widely used for studying dispersion.

Mean deviation is a measure that removes several shortcomings of other measures i.e. it does not ignore extreme terms or values which play a significant role in average or Mean.

Absolute measures of Dispersion are expressed in same units in which original data is presented but these measures cannot be used to compare the variations between the two series.

So going through the merits and demerits, we conclude that Quartile Deviation cannot be relied on blindly.

Merits and Demerits of Range...

Literally, dispersion means deviation, difference or spread of certain values from their central value. In relation to statistical seris, it means, deviations of various items of the series from its ventral value.

The use or application of a particular average depends upon the purpose of the investigation. Some of the cases of different averages are as follows:

What are the Merits and Demerits of Harmonic Mean?

What are the Merits and Demerits of Geometric mean (GM)?

What is the Empirical relation between Mean, Mode and Median?

Mode may be defined as the value that occurs most frequently in a statistical distribution. In French language 'Mode' means 'Fashion'.

What are the Merits and Demerits of Median?

According to A.L. Bowley, "Statistics may rightly be called as the science of averages." This average is also known as central value. Through statistical analysis we condense the whole data to a single value, which represents the data in true sense.

The series dealing with the continuous variable is called continuous series. The continuous variable is one which can assume any conceivable fractional value within a range.

The series dealing with the discrete variable is called Discrete Series. The discrete variable refers to that characteristic which cannot be expressed in fractions or it is a frictionless variable.

What are the various kinds of continuous series?

The process of arranging the data in groups or classes according to their common characteristics is technically known as classification.

Tabulation refers to the systematic arrangement of the information in rows and columns. Rows are the horizontal arrangement. In simple words, tabulation is a layout of figures in rectangular form with appropriate headings to explain different rows and columns.

In practical life, schedule or questionnaire have same meaning. But in theoretical aspect, difference is made between a schedule or questionnaire.

According to this method, the investigator obtains the data by a personal interview or observation i.e. he contacts the source of information directly and personally.

What are the difference between Primary and Secondary data?

It refers to the statistical material which is not originated by the investigator himself but obtained from some one else's records, or when Primary data is utilised for any other purpose at some subsequent enquiry it is termed as Secondary data.

It refers to the statistical material which the investigator originates for himself for the purpose of the enquiry in hand.

According to Lord Kalvin, "When you can measure what you are speaking about and express it in numbers, you know something about it, but when you cannot measure it and you cannot express it in numbers, your knowledge is of meager and unsatisfactory kind."