Avudaiappan Dharma

Measures of Variability        Measures of central tendency, such as the mean and the median described in article 2 (22.02.2019) provide useful information. But it is important to recognize that these measures are limited and, by themselves, do not provide a great deal of information. There are three measures of dispersion that researchers typically examine: the range , the v ariance , and the standard deviation . Of these, the standard deviation is perhaps the most informative and certainly the most widely used. Range The range is simply the difference between the largest score (the maximum value ) and the smallest score (the minimum value ) of a distribution. Squared deviation The difference between an individual score in a distribution and the mean for the distribution, squared. Variance The variance provides a statistical average of the amount of dispersion in a distribution of scores. The other word sum of the squared deviation...

Descriptive Statistics In my last (21.2.2019) article, I was discussed about basic of Basics of Statistics. In this article, we are going to discuss about Descriptive Statistics. Variety of Descriptive statistics ·          Measures of   Central Tendency - Mean, Median, Mode ·          Measures of   Dispersion - Range, Variance, Std Deviation ·          Measures of Shape - Skewness, Kurtosis These descriptive statistics are used to help describe data, especially when we are dealing with very large data sets. Why is it important to learn about summary statistics? Ø   Description of large number of data points Ø   Generate inferences from the summary statistics Measures of Central Tendency Distribution: A collection, or group, of scores from a sample on a single variable. Often, but not necessarily, these scores are arranged...

In this Article, review some of the fundamental research principles and terminology including the distinction between samples and populations, methods of sampling, types of variables, and the distinction between inferential and descriptive statistics. Statistic: A characteristic, or value, derived from sample data. Descriptive statistics: Statistics used to describe the characteristics of a distribution of scores. Inferential statistics: Statistics, derived from sample data that are used to make inferences about the population from which the sample was drawn. Parameter: A value, or values, derived from population data. A population is an individual or group that represents all the members of a certain group or Category of interest. A sample is a subset drawn from the larger population. Sample: A collection of cases selected from a larger population. Random sample (or random sampling): Selecting cases from a population in a manner that ensures each me...