Types of Data

The first step of any statistical enquiry is the collection of relevant numerical data. The types of data used for statistical purposes is mainly classified as primary data and secondary data


a characteristic of population that can take different values (e.g., defects, processing time).


Data are measurements collected on a variable

Primary Data

Data collected for the purpose of the given inquiry is called as Primary Data. These are collected by the enquirer, either by his own or through some agency set up for this purpose, directly from the field of enquiry. This type of data can be used with greater confidence because the enquirer himself decides upon the coverage of the data, definitions to be used and as such will have a greater control over the reliability of the data.

Secondary Data

The data already collected by some other agency or for some other purpose and available in published or un published form is known as secondary data. The user has to be perticularly careful about using using such data. The user must clearly understand the nature of the data, their coverage, the definitions used for the data and their reliability.
The usage of secondary data is generally preferred if the conditions mentioned above are clear and usable. This will reduce the time taken for the analysis, also reduces cost of the analysis.

Types of data

Discrete Data

Count or frequency of occurrence

Attribute Data

Data which on one of a set of discrete values such as pass or fail, yes or no.

Continuous Data

Measurements that can be meaningfully divided into finer and finer increments of precision

Usage of Sampling

The big question is weather the collection of data should be done by complete population or by sampling. If sample is used, care should be taken that this is a representative of complete population. A sample designed with care can produce results that may be sufficiently accurate for the purpose of enquiry. A Carefully designed sample can save a lot of time and money.

Methods of Data Collection

The methods used to collect data are Questionnaire Method, Interview Method and Direct Observation Method. Any one or a combination of these are used to collect data.

Usage of Data

The data collected should be subjected to a thorough scrutiny to see if they may be considered correct. The success of the analysis depends on the reliability of the data. However excellent the statistical method of data analysis may be, they cannot bring out useful and reliable information from faulty, unreliable of mistaken data. Especially, this is more applicable in case of usage of secondery data.

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Originally posted 2011-10-01 11:14:00.

Statistics – 1 – What is Statistics ?

Statistics can be described as a quantitative method of scientific investigations.
If used as  plural noun ‘Statistics’ means the numerical data arising out of any sphere of human experience.
Used as singular ‘Statistics’ is the name for the body of scientific methods used for collection, analysis, Organizing, and interpretation of Numerical data.
According to American Statistical Association “Statistics” is the scientific application of mathematical principles to the collection, analysis, and presentation of numerical data’
Also, There is a different meaning for the word ‘Statistic’ in the field of Statistics(subject). In this sense A ‘Statistic’ is a numerical item which are produced by the some calculations using the data. Standard Deviation, Mean etc are called as ‘Statistic’  in this sense.
This is one arm of Mathematics, which is extensively used in all most every field. It has become an important tool in the work of many academic disciplines such as medicine, psychology, education, sociology, engineering and physics, just to name a few. It is also important in many aspects of society such as business, industry and government. Because of the increasing use of statistics in so many areas of our lives, it has become very desirable to understand and practice statistical thinking. This is important even if you do not use statistical methods directly.
Even with so many uses, there is some mistrust in public about the subject. This is because of the misuse of the figures by the people for their convenience. During the introduction to the course i joined on, this statement is used. There are 3 types of lies. 1 – Lies, 2- damned Lies 3-Statistics. We will teach you the 3rd part here.
Used properly statistics is a panacea for all the problems faced by the world. it can be a tremendous tool for the growth of any organization. 
Visit the next post Data Collection – Types of Data
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Originally posted 2011-09-30 20:00:00.

What is Six Sigma – History

Six Sigma Methodology has its origin from Motorola, has an interesting history. Sigma is Greek for the letter ‘S’, and the term ‘sigma’ has been used for many years by statisticians, mathematicians and engineers, as a measurement unit of statistical variation till it was integrated into the quality System and business strategy by Motorola in 1987.

The seeds of this concept go back to 19790 when the Japanese management took over a TV manufacturing division of Motorola.  The Japanese concentrated on the quality of the output and actually reduced the defects to 5% of defects when the same unit was managed by Motorola. This result made the Motorola Management to take serious note of Quality.

The actual push came in Motorola only after 1981, When Bob Gavin became the CEO of Motorola. He targeted a 10 fold increase in performance within a 5 year period.

The Motorola Engineers Bill Smith or Mikal Harry – felt that measuring defects in terms of thousands was Not Sufficient for achieving a rigorous standard. They increased the measurement scale to parts per million, described as ‘defects per million’, which prompted the use the the ‘six sigma’ terminology and adoption of the capitalized ‘Six Sigma’ branded name, given that six sigma was deemed to equate to 3.4 parts – or defects – per million opportunities.

This has caught the eye of Gavin and launched the program Called “The Six Sigma Quality Program” on 15th Jan 1987. Stringent Targets were set to achieve Six Sigma Capability in 5 years. Astronomical Targets like 10 fold increase by 1989, and 100 fold increase by 1991 and Six sigma capability by 1992. A deep Sense of urgency was shown and every part of the organization was made to obsess with Six Sigma.

Soon after the success of Motorola, Allied Signal ( Now a part of Honeywell) plunged into this concept and achieved success.

The biggest push to Six-Sigma was given by Jack Welch the CEO of General Electric (GE) in 1995. He believed the possible improvement that can be achieved by this change and imbibed into the culture of the company. There were rewards, targets and training which were incorporated. By 1998, GE Reported a savings of more than three quarters of billion in profits.

By the year 2000, Six Sigma was effectively established as an industry in its own right, involving the training, consultancy and implementation of Six Sigma methodology in all sorts of organizations around the world.

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Originally posted 2011-03-21 16:55:00.