Outliers - reasons for screening data, Advanced Statistics

Assignment Help:

Outliers - Reasons for Screening Data

Outliers are due to data entry errors, subject is not a member of the population that the sample is trying to represent, or the subject is really different. Statistical tests are quite sensitive to outliers so this problem should be addressed.

Univariate outliers are easy to detect (z-scores, box plots, histograms, etc.) standard scores larger than +/-3 are outliers (consider 4 is n>100 or 2.5 if n<10)

Multivariate outliers are difficult to detect. Mahalanobis distance is one powerful technique to use in this case (discussed later). This is evaluated as a chi-square statistic with degrees of freedom equal to number of variables in the analysis. A chi-sqaure statistic value that is significant beyond p<0.001 level determines outliers.

In most cases, it is ok to drop the value from the sample. One can also take steps to reduce the relative influence of outliers if the researcher decides to include the values in the analysis.


Related Discussions:- Outliers - reasons for screening data

Multitrait multi method model (mtmm), Multitrait multi method model (MTMM) ...

Multitrait multi method model (MTMM) is the form of confirmatory factor analysis model in which the different techniques of measurement are used to measure each of the latent vari

Glejser test, Glejser test is the test for the heteroscedasticity in the e...

Glejser test is the test for the heteroscedasticity in the error terms of the regression analysis which involves regressing the absolute values of the regression residuals for the

Explain lattice distribution, Lattice distribution : A class of probability...

Lattice distribution : A class of probability distributions to which most of the distributions for discrete random variables used in statistics belongs. In such type of distributio

Expected frequencies, A term commonly encountered in the analysis of the co...

A term commonly encountered in the analysis of the contingency tables. Such type of frequencies are the estimates of the values to be expected under hypothesis of interest. In a tw

Collector''s problem, Collector's problem : A problem which derives from th...

Collector's problem : A problem which derives from the schemes in which packets of a particular brand of coffe, cereal etc., are sold with coupons, cards, or other tokens. There ar

Define Geo statistics, Geo statistics: The body of methods useful for unde...

Geo statistics: The body of methods useful for understanding and modelling spatial variability in a course of interest. Central to these techniques is the idea that measurements t

Define hazard function, Hazard function : The risk which an individual expe...

Hazard function : The risk which an individual experiences an event in a small time interval, given that the individual has survived up to the starting of the interval. It is th

Residual plots, Residual plots are the plots of some type of residual whi...

Residual plots are the plots of some type of residual which might be helpful in assessing the assumption made by the fitted model. In regression analysis there are various method

Advanced managerial statistics, The objective of this assignment is to test...

The objective of this assignment is to test your understanding in the learning outcome (LO2) and learning outcome (LO3) and learning outcome (LO4). 1) This is a grouped assignme

Leaps-and-bounds algorithm, Leaps-and-bounds algorithm is an algorithm whi...

Leaps-and-bounds algorithm is an algorithm which is used to ?nd the optimal solution in problems which might have a large number of possible solutions. Begins by dividing the poss

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd