Skip to main content

parametric and non parametric test ( review)

parametric test
Parametric statistics is a branch of statistics which assumes that sample data comes from a population that follows a probability distribution based on a fixed set of parameters.Most well-known elementary statistical methods are parametric
or 
we can say that a parametric test is one that make assumptions about the parameters of the population distribution from which ones data is drawn

or 
parametric test is a test in which we check if the simple is come from the certain population parameters which are drawn from population. 
its focus on fixed population.

Non parametric test

non parametric test differs from parametric test it is mostly use when the assumption of parametric test does not fulfill and our data is not normal.

now what is meant by normal data the assumptions are given below(if the following assumptions does not fulfill then we use non parametric test)
  1. sample size
 for parametric test the sample size should be large <50 we use z test
but if the sample size is >50 we can also use parametric test t test.

2. normal distribution
if our data is normally distributed then we use parametric test . this can be check by descriptive statistics. frequency distribution and from skewness and kurtises

·         Skewness and Kurtosis: To test the assumption of normal distribution, Skewness should be within the range ±2.  Kurtosis values should be within range of ±7
·         Shapiro-Wilk’s W test: Most of the researchers use this test to test the assumption of normality.  Wilk’s test should not be significant to meet the assumption of normality.
·         Kolmogorov-Smirnov test: In the case of a large sample, most researchers use K-S test to test the assumption of normality.  This test should not be significant to meet the assumption of normality.
Graphical method for test of normality:
·         Q-Q plot: Most researchers use Q-Q plots to test the assumption of normality.  In this method, observed value and expected value are plotted on a graph.  If the plotted value varies more from a straight line, then the data is not normally distributed. Otherwise data will be normally distributed.
Assumptions of homogeneity of variance:
·         Levene’s test: To test the assumption of homogeneity of variance, Levene’s test is used.  Levene’s test is used to asses if the groups have equal variances.  This test should not be significant to meet the assumption of equality of variances
Homogeneity of variance-covariance matrices assumption:
·         Box’s M test: This test is used to test the multivariate homogeneity of variance-covariance matrices assumption.  An insignificant value of Box’s M test shows that those groups do not differ from each other and would meet the assumption
Randomness: Most of the statistics assume that the sample observations are random.  Run Test is used to test the assumption of randomness.
Multicollinearity: Multicollinearity means that the variables of interest are highly correlated, and high correlations should not be present among variables of interest.  To test the assumption of multicollinearity, VIF and Condition indices can be used, especially in regression analyses.  A value of VIF >10 indicates multicollinearity is present and the assumption is violated.


Comments

Post a Comment

Popular posts from this blog

ADAPTIVE BEHAVIOR ASSESSMENT SCALE (ABAS-II)

what is ABAS? The adaptive behavior assessment system (ABAS-II) provides a comprehensive norm-referenced assessment of adaptive skills for individual’s age birth to 89 years. The ABAS-II can be used to assess an individual’s adaptive skills for assessment and diagnosis and classification of disabilities and disorders, identification of strengths and limitations, and to document and monitor an individual’s progress over time. The ABAS-II measures ranges of adaptive skills according to American Association on Mental Retardation (AMAR) and Diagnostic and Statistical Manual of Mental Disorders- Fourth Edition (DSM-IV). It is a complete assessment tool to measure multiple respondents, evaluating functioning across multiple settings and to assessment of daily functioning’s of an individual. The basic components of ABAS-II include the manual and five rating forms. Relevant respondents of the person being evaluated can rate these forms. Respondents can be parents, teachers, family membe...
4 comments
Read more

what is Dyslexia screening test junior and how to apply it?

    THE DYSLEXIA SCREENING TEST Junior (6years 6months to 11years 5months) Introduction The revised Dyslexia Screening Test now covers primary and secondary school-aged children in two separate assessments. The division of the DST into two tests, DST - Junior and DST - Secondary, include extra subtests which are particularly relevant to the age group. The DST-J provides a profile of strengths and weaknesses which can be used to guide the development of in-school support for the child. New theoretical developments in dyslexia research suggest that it should be possible to identify both slow learners and potential dyslexic children at the age of 5 or 6 years, in time for greater reading support. The DST-J is designed for early identification of children who are at risk of reading failure so that they can be given extra support at school . What is dyslexia?? It can be defined as difficulty in learning, reading, or interpreting words, letter, other ...
Post a Comment
Read more

what is beck hopeless scale?

 Back hopelessness Scale INTRODUCTION Background and development The back hopelessness scale(BHS; Beck’ weissman, lester, &trexler, 1974) IS A 20 item scale for measuring the extent of negative attitude about the future (pessimism)as perceived by adolescents and adult. The BHS was originally developed by Aron T. Beck and his associates the center for cognitive theropy (CCT), University of Pennsylvania Medical School, Department of psychiatry, to measure pessimism in psychiatric patients consider tobe suicidal risks, but it has been used subsequently with adolescent and adult normal population. Hopelessness is a psychological construct that has been observed to underlie a variety of mental health disorder. After reviewing the literature on the hopelessness construct.  Stotland (1969) concluded that although many cliniciansbelievedthat hopelessness wastoodifuse to be measured systematically, there was sufficient consensus to construct an instrument to evaluate negative attit...
Post a Comment
Read more