Explain missing values, Advanced Statistics

Assignment Help:

Missing values: The observations missing from the set of data for some of the reason. In longitudinal studies, for instance, they might occur because subjects drop out of the study completely or do not appear for one or other of scheduled visits or because of the equipment failure. The common causes of subjects prematurely ceasing to participate include the recovery, lack of improvement, the unwanted signs or symptoms that might be related to the investigational treatment, unlikeable study procedures and the intercurrent health problems. Such values greatly complicate number of methods of analysis and simply using those individuals for whom data are complete can be unsatisfactory in number of situations. A distinction can be made between the values missing completely at random (MCAR), missing at random (MAR) and the non-ignorable (or informative).

The MCAR variety arise when the individuals drop out of study in a process which is independent of the observed measurements and those that would have been available had they not been missing both; here the observed values effectively constitute the simple random sample of the values for all study subjects. Random drop-out (MAR) happens when the dropout process depends on the outcomes which have been observed in the past, but given this information is conditionally independent of all future (which is unrecorded) values of the outcome variable following the drop-out. At last, in the case of informative drop-out, the drop-out process depends upon the unobserved values of the result variable. It is the latter which cause most the problems for the analysis of data comprising missing values.


Related Discussions:- Explain missing values

Omitted covariates, Omitted covariates is a term generally found in the co...

Omitted covariates is a term generally found in the connection with regression modelling, where the model has been incompletely specified by not including significant covariates.

Bonferroni correction, Bonferroni correction : A procedure for guarding aga...

Bonferroni correction : A procedure for guarding against the rise in the probability of a type I error when performing the multiple signi?cance tests. To maintain probability of a

Cluster randomization, Cluster randomization : The random allocation of the...

Cluster randomization : The random allocation of the groups or clusters of the individuals in the formation of treatment groups.Eeven though not as statistically ef?cient as the in

Computer-intensive methods, Computer-intensive methods : The statistical me...

Computer-intensive methods : The statistical methods which require almost identical computations on the data repeated number of times. The term computer intensive is, certainly, a

Captures recapture sampling, Captures recapture sampling : Another approach...

Captures recapture sampling : Another approach to a census for estimating the size of population, which operates by sampling the population number of times, identifying the individ

Lexis diagram, Lexis diagram  is the diagram for displaying the simultaneou...

Lexis diagram  is the diagram for displaying the simultaneous effects of the two time scales (generally age and calendar time) on a rate. For instance, mortality rates from cancer

Quittingill effect, Quittingill effect is a  problem which occurs most fre...

Quittingill effect is a  problem which occurs most frequently in studies of the smoker cessation where smokers frequently quit smoking following the onset of the disease symptoms

Find the expected value of perfect information, You may have the opportunit...

You may have the opportunity to buy some electronic components. These components may be reliable (1) or unreliable (2). The potential pro?ts are £10,000 if the components are rel

Adjusted r-squared, R-squared is regarded as the coefficient of determinati...

R-squared is regarded as the coefficient of determination and is used to give the proportion of the fluctuation of the variance of one variable to another variable. R-squared also

Discriminant analysis, A term which covers the large number of techniques f...

A term which covers the large number of techniques for the analysis of the multivariate data which have in common the aim to assess whether or not the set of variables distinguish

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