International Journal of Probability and Statistics 2016, 5(1): 10-17 DOI: 10.5923/j.ijps.20160501.02 Performance Assessment of Penalized Variable Selection Methods Using Crop Yield Data from the Three Northern Regions of Ghana Smart A. Sarpong 1,* , N. N. N. Nsowah-Nuamah 2 , Richard K. Avuglah 3 , Seungyoung Oh 4 , Youngjo Lee 4 1 Institute of Research, Innovations and Development - IRID, Kumasi Polytechnic, Ghana 2 Kumasi Polytechnic, Ghana 3 Department of Mathematics, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana 4 Department of Statistics, Seoul National University, South Korea Abstract Time and money can be saved by measuring only relevant predictors. Measuring relevant predictors also ensures a noise free estimation of parameters and preserves some degrees of freedom for a given predictive model. By comparing the performance of SCAD, LASSO and H-Likelihood, this study seeks to select among access to credit, training, study tour, demonstrative practicals, networking events, post-harvest equipments, size of plot cultivated and number of farmers; variables (fixed and interaction terms) that significantly influences crop yield in the three Northern regions of Ghana. Our simulation as well as real life results gives evidence to the fact that H-Likelihood method of penalized variable selection performs best followed by SCAD, with LASSO coming last. It does both selection of significant variables and estimation of their coefficients simultaneously with the least penalize cross-validated errors compared to the SCAD and the LASSO. The study therefore recommends that deliberate efforts be put into strengthening the Agricultural support systems as a form of strategy for increasing crop production in Northern Ghana. Keywords Penalized, SCAD, LASSO, H-likelihood, PCVE, Variable Selection, Crop yield 1. Introduction The rate of food production in many parts of sub-Saharan Africa has not kept pace with the rate of population growth. Whereas the estimates of population growth rate increase at about 3 per cent annually, that of food production increases by only 2 per cent (Rosegrant et al., 2001). The sub-region's per capita deficit in grains and cereals according to Rosegrant et al., (2001) is one of the highest in the world. Way back in 1967, the sub-region's cereal imports was 1.5 million tons. However, just within thirty years down the way, this figure increased to 12 million tons in 1997, and projections have it that the sub-region will require about 27 million tons of cereal imports to satisfy demand by 2020 (Rosegrant et al., 2001). In the long run, importation may not be economically feasible to ameliorate food shortages. Thus, there is a need to increase domestic production to guarantee food security. Ghana is still recognized worldwide as an agriculture-based economy. Agriculture has been the anchor * Corresponding author: smartsarpong2015@gmail.com (Smart A. Sarpong) Published online at http://journal.sapub.org/ijps Copyright © 2016 Scientific & Academic Publishing. All Rights Reserved of Ghana’s economy throughout post-independence history (McKay and Aryeetey, 2004). While policy and political instability had induced the fall of per capita GDP growth until 1980s, the agricultural sector had been less affected due to less interventions by the government compared to the non-agricultural sector and the fact that its growth is mainly led by smallholder farmers for subsistence purposes. Beyond 1992 when Ghana gained the forth republican political stability, there has been a rapid growth in the nonagricultural sectors; expanding by an average rate of 5.5 percent annually, compared to 5.2 percent for the entire economy (Bogetic et al., 2007). The analysis presented in this paper suggests that a system of support services; Access to credit facility, Training, Study tour, Demonstrative practical, Networking events and Post-harvest Equipments, plays an important role in determining crop yields even though their individual and interaction effects on yield is not uniform across farmer base organizations. This research focuses primarily on the production of Maize and Soy beans in northern region of Ghana where there exists considerable farming activity. Maize and Soy beans are the very much cultivated in these parts of the country due to their vegetation which supports the growth of grains and cereals. Beyond the numbers and descriptive statistics on yield of such crops, this study tries to