Sources of Data

The foundation of data analysis in statistics lies in the collection of data. Data is nothing but unorganised facts and figures which are collected for a certain purpose, like an analysis. The medium through which data is collected is termed as a source of data.

Sources of data are of two types; these are the following – 

  • Statistical Data

This type of data source refers to collection of data which are used for official purposes, such as population census, official surveys, etc.

  • Non-Statistical Data

This type of data source refers to collection of data which are used for various administrative purposes, mainly in the private sectors. 

Different Sources of Data

Sources of data can also be classified based on its collection methods, which are –

  • Internal Sources of Data

In several cases for a certain analysis, data is collected from records, archives, and various other sources within the organisation itself. Such sources of data are termed as internal sources of data.


A school is performing an analysis to figure out the highest marks achieved in class 8 science subjects for the last 10 years.

  • External Sources of Data

Data may also be collected from various sources outside the organisation for analytical purposes. Such sources of data collection are known as external sources of data. 


As a patient, you are analysing the price charts of your nearby hospitals for treatment of ulcer.

Check Your Progress –

Q. What are Different Types of Data Sources?

Sources of data can be categorised as per two basis points, i.e. purpose of data collection and type of data source. This can be explained with the help of an illustration given below –

Types of Data

Data can be classified into two types –

  • Primary Data

Data which is considered as first-hand information collected by a surveyor, investigator, etc. is defined as Primary Data. The sources from which such data is collected is termed as the primary source of data collection for the concerned information.

Moreover, data is regarded as primary only if it has never undergone any prior statistical treatment. Such data is usually published, and more data is derived from the published source for other purposes. For example, a country’s population is an application of collection of primary data.

Features of Primary Data

Primary Data has the following characteristics –

  1. Such data is being collected for the first time.

  2. Primary Data is original and thereby more reliable than other types of data

  3. This kind of data has not been used for any statistical analysis before. 

  • Secondary Data

Data which has already been collected, analysed, published and has undergone statistical treatment can be defined as Secondary data. Such type of data is tailored from primary data sources.

However, this kind of data can also be collected by surveyors, investigators, etc. to conduct statistical analysis in order to derive newer information.

For example, the address you insert in food delivery apps is a common application for the use of secondary data. Your address is not new information unless you just purchased a property. 

In such cases, information regarding the address of your new property will be considered as primary data. From this example, you can get a clear understanding of the sources of data primary and secondary.

Features of Secondary Data

Secondary Data consists of the following features –

  1. Secondary data is considered as ‘second-hand information’.

  2. Secondary data is not original.

  3. This kind of data has gone through statistical analysis at least once.

  4. Secondary data is not reliable.

Another simple example of Secondary Data is information which is found in unapproved websites such as Wikipedia, etc. where any user at any given time can edit the data, as per his or her wish, provided in any page of this website.

Methods of Collecting Data in Statistics

Data collection is a standout procedure carried out by most analysts during research. As an analyst, if you are unable to collect the necessary data for your research, your whole venture will lose its credibility.

So, data collection is an essential element in statistical analysis; it is a challenging duty which requires dedication, determination, proper planning and the capability to finish the assignment. 

The primary step of data collection is figuring out what kind of data is required and then starting your analysis by collection of a sample through a specific sampling method from a certain part of the population.

There are various methods of data collection which can be classified as per the type of data involved, which are –

A. Collection of Primary Data

Collection of Primary Data can be done through various methods, which are –

  • Direct Personal Investigation

In this method, surveyors or investigators collect the data themselves. This method is suitable for small projects where the required data needs to be reliable and excessive effort is not mandatory.

  • Collection with the Help of Investigators

In this method, a single or a group of correspondents collects the data for the surveyor. These correspondents are trained investigators who are employed for this course of action. This type of data collecting method is useful for a large population.

  • Collection Assisted by Questionnaires

When the amount of data which is required to be collected is significantly large, questionnaires are used to make the data collecting process easier. Questionnaires are nothing but a set of questions which, when answered, provide the required data. Surveyors can also mail questionnaires to the respondents for added convenience.

B. Collection of Secondary Data

Collection of secondary data is much easier than collecting primary data. Secondary data is available on various sources, both published and unpublished. 

However, the investigator of this kind of data must ensure that the data is reliable, suitable for analysis, whether bias is involved during sampling of the said data, etc.

At Vedantu, we hope that this study material will help you to fetch top marks in the upcoming Statistics exams! You can also install the Vedantu app in your smartphone to instantly access all our best-in-class study materials. 

FAQ (Frequently Asked Questions)

1. What are the Different Types of Data Sources Based on the Type?

Ans. Based on the type, sources of data are of two types, which are internal sources and external sources.

2. State the Methods of Collecting Primary Data.

Ans. The various methods of collecting primary data are direct investigation, telephonic investigation, investigation through questionnaires, investigation through correspondents.

3. What are the Features of Secondary Data?

Ans. Secondary data is considered as second-hand information since it has already been under statistical treatment. It is not original, nor it is reliable, and usually, sampling of secondary data involves bias.