# Basic Statistics I – Definitions of commonly used Statistical Terms

When talking of statistics, we come across many simple terms. These Basics are called as basic statistics. we come across them day in and day out, when ever we are working on any statistics. Without these basic statistics terms, we cannot understand anything with respect to our statistical problem. Most of them are also used in our daily life, but may be with a different name in statistics

• Average – Also called the mean, it is the arithmetic average of all of the sample values. It is calculated by adding all of the sample values together and dividing by the number of elements (n) in the sample.
• Central Tendency – A measure of the point about which a group of values is clustered; two measures of central tendency are the mean, and the median.
• Characteristic – A process input or output which can be measured and monitored.
• Cycle Time – The total amount of elapsed time expended from the time a task, product or service is started until it is completed.
• Long-term Variation – The observed variation of an input or output characteristic which has had the opportunity to experience the majority of the variation effects that influence it.
• Median – The middle value of a data set when the values are arranged in either ascending or descending order.
• Mode : The data point which occurs at maximum frequency
• Lower Control Limit (LCL) –  for control charts: the limit above which the subgroup statistics must remain for the process to be in control. Typically, 3 standard deviations below the central tendency.
• Lower Specification Limit (LSL) – The lowest value of a characteristic which is acceptable.Range – A measure of the variability in a data set. It is the difference between the largest and smallest values in a data set.
• Specification Limits – The bounds of acceptable performance for a characteristic.
• Standard Deviation – One of the most common measures of variability in a data set or in a population. It is the square root of the variance.
• Trend – A gradual, systematic change over time or some other variable.
• Upper Control Limit (UCL) for Control Charts – The upper limit below which a process statistic must remain to be in control. Typically this value is 3 standard deviations above the central tendency.
• Upper Specification Limit (USL) – The highest value of a characteristic which is acceptable.
• Variability – A generic term that refers to the property of a characteristic, process or system to take on different values when it is repeated.
• Variables – Quantities which are subject to change or variability.
• Variable Data – Data which is continuous, which can be meaningfully subdivided, i.e. can have decimal subdivisions.
• Variance – A specifically defined mathematical measure of variability in a data set or population. It is the square of the standard deviation.

Originally posted 2011-10-20 12:53:00.

# 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.
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