Saturday, December 24, 2011

Statistical techniques

Definition of Statistics

Statistics are mathematical techniques  for analyzing numerical data to accomplish various purposes. For example the calculation of a mean leads to a single score that represents many scores such as the scores of all students who took a particular test.

Types of Statistics

There are four types of Statistics: descriptive, correlational, inferential and psychometric.

Descriptive Statistics

Descriptive Satistics are mathematical techniques for organizing and summarizing a set of numerical data. In Educational Research they are used to describe educational phenomena. They describe the score on a single variable

Correlational Statistics

Correlational Statistics are used to describe relationships between two or more variables.

Inferential Statistics

Inferential Statistics are mathematical techniques for using probabilities and information about a sample to draw conclusions about the population from which the sample originated.

Psychometric Statistics

They are Statistics used to describe the psychometric properties of tests and he appropriateness of information and uses of outcomes from tests and other measures.

Example of Statistical Analysis in a Research Study

Statistics are used in virtually all quantitative studies but in many qualitative studies also. An example is the case study of reading groups in a first grade classroom conducted by James Collins. The study was part of a large ethnographic study of language differences between working class black children and middle class white children in their home and school environments.

Types of Scores 

Measurements in educational research are expressed usually in three forms: continuous scores, ranks, or categories. It is important to understand the differences between the score types because the forms in which the scores are expressed reflect the choice of statistical analysis procedure. If the research data consist of continuous scores on two groups group differences are analyzed by calculating a mean score and a statistic known as t. However if the scores are in thew forms of categories the group differences are analyzed by a Chi-square test, which compares categories frequencies between two or more groups. There are 3 types of scores: continuous, age and grade equivalents and rank.

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