Introduction to statistics

What is Statistics?

Statistics is the methodology for collecting, analyzing, interpreting and drawing conclusions from collected data.
Definition 1.1 (Statistics). Statistics consists of a body of methods for collecting
and analyzing data. (Agresti & Finlay, 1997)

Statistical methods can be used to find answers to the questions like:

1. What kind and how much data need to be collected?
2. How should we organize and summarize the data?
3. How can we analyse the data and draw conclusions from it?
4. How can we assess the strength of the conclusions and evaluate their uncertainty?

That is, statistics provides methods for

• Design: Planning and carrying out research studies.
• Description: Summarizing and exploring data.
• Inference: Making predictions and generalizing about phenomena represented by the data.

Nature of data:

1. Primary data
2. Secondary data

Primary data: Data observed or collected directly from first-hand experience for a specific purpose and is use for that purpose.

—Advantage: Suits purpose

—Disadvantage: Time Consuming and Costly

Secondary data: Information that has been collected for a purpose other than your current research project but has some relevance and utility for your research.

Advantage: Often cheaper than collecting primary data

Disadvantage: It may not exactly fit your research questions

Type of data: 

Qualitative and Quantitative

Qualitative: [(Binary) and (many valued: Nominal and Ordinal)]

Quantitative: [Discrete and Continous]

              Categorical data/Qualitative data: data which can be placed into categories which are                                                         mutually exclusive for example age group.

—Discrete data: generally, discrete data are counts
Continuous data: generally, continuous data come from measurements

Population/ census vs sample

Mode of sampling a questionnaire: 
1. By observation
2. By face to face interviewing.
3. Postal method
4. Telephone method

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