The trade-off between the PLSR and PCR methods for modeling data with collinear structure

This paper investigates the partial least squares regression (PLSR) and principal component regression (PCR) methods as versatile alternative regression techniques when the use of the ordinary least squares method breaks down. Emphasis is more on the situation where the predictor variables are evidently correlated. Data sets with Gaussian non-orthogonal predictor variables were simulated at different sample sizes ranging from 20 to 1000 to examine the performance of the two regression types under varying situations. The data were randomly partitioned into training and test sets with both PLSR and PCR models constructed on the training sets while their performances were evaluated on the test sets using themean square error of predictions and other indices. At each fit of the models, the leave-one-out cross-validation technique was employed to enhance the efficiency and stability of the fitted models. Results from the simulation studies revealed the goodness of the two regression methods but at varying degrees of accuracy. More importantly, it is evident from the results that though, both the PLSR and PCR techniques yielded good regression models, the PLSRtechniqueis consistently more efficient on the test datain terms of good predictions than the PCR method irrespective of sample sizes. Also in terms of model parsimony, the PLSR technique yielded efficient regression models with relatively fewer latent components than the PCR method. Data sets on the performance of M.Sc. graduates from the Department of Statistics, University of Ilorin, Nigeria during the 2012 academic session were used to validate the results from the Monte Carlo studies

Anti-Kell allo-immunization in a Tertiary Care Hospital in North central Nigeria

Objective: Although ABO and Rh are the most clinically important blood group systems, other systems are also immunogenically significant. After ABO and Rh systems, anti-K, anti-k, anti-Kpa, anti-Kpb, anti-Jsa, anti-Jsb, and anti-U1a, were the next to cause acute and delayed haemolytic transfusion reactions and Haemolytic Disease of Fetus and Newborn. Design: A prospective cross-sectional study. Subjects: 300 adult patients who had one or more units of packed cells or whole blood for correction of anaemia. Interventions: antibody screening, identification and titration was performed using commercially prepared panel of cells on the serum obtained by centrifuging 2ml of venous blood aspirated from every blood transfusion recipient 48 hours after transfusion. Result: Anti-K allo-immunization in this study was 1.6%. Anaemia and bleeding associated with pregnancy and other obstetrics and gynaecology disorders, Diabetes Mellitus and cancer of the bladder were indications for transfusions in 60%, 20% and 20% respectively of the 5 anti-K allo-immunized recipients. Female sex and previous blood transfusions correlated significantly with anti-K  alloimmunization while age, types of unit transfused, and types of transfusion did not. All the anti-K allo-antibodies were of the IgG while 2 were of IgG + IgM type. Conclusion: Because of the high prevalence of anti-K in this study, antibodies screening and identification is recommended to improve  blood transfusion safety