school principals and teachers are present in school when they see fit, resulting in serious problems of lateness and absenteeism and low teacher-pupil contact hours (MOESS, 2008).

As is the case in some other developing countries, the public perception is that private schools have higher educational standards compared to public schools in both urban and rural areas; this perception is reinforced by the better performing private school pupils at various assessments such as the School Education Assessment (SEA), the National Education Assessment (NEA) and the Basic Education Certificate Examination (BECE). In 2007/8, private school enrolment stood at 24% of the total national enrolment, while the number of private schools increased by 36% between 2005/6 and 2007/8 (from 2,990 to 4,068. The main advantage of private schools is that they facilitate better English language skills; however, they also provide more access to extra classes and special tuition to students (Ampiah, 2008; 2010).

Practices relating to language of instruction are also important. In Ghana, there are two languages involved in basic education: the child’s own vernacular as well as English language, which is more widely used in education. From primary 4 onwards, the English language becomes the medium of instruction (as well as a school subject). A relatively recent decision by the Ministry of Education has been to develop quality bilingual literacy instruction in all primary schools. However, implementation challenges remain, as some teachers are not functional in local languages, most classes in urban areas are multilingual and textbooks, while written in English are taught in the local language (Ampiah, 2010). Based on the outcome of TIMSS 2007, the majority of the Ghanaian 8<sup>th</sup> grade students (66%) rarely spoke English at home – if ever – and the home language was found to be associated with lower achievement in both mathematics and science (Anamuah-Mensah, Mereku and Ampiah 2008).

Finally, there are problems resulting from high proportions of untrained teachers in basic education. Low retention and high attrition rates resulted in a discrepancy between trained teachers in basic education and the output of the Teacher Training Colleges in Ghana. This resulted in large numbers of untrained teachers filling teacher vacancies. In 2007, the proportion of untrained teachers in Junior high school stood at 33% (MoESS 2007).

# **2. Methodology**

# _2.1 General_

Decomposition methods are frequently used in an attempt to answer important questions, such as what accounts for pay differences between men and women, what is behind increases in wage inequality in recent times, among others. They have also been applied in a variety of other settings, including the study of gaps in test scores between schools (Krieg and Storer 2006), men and women (Sohn 2008) and countries (McEwan and Marshal 2004; Ammermueller 2007).

In the last 10-15 years there has been an evolution and refinement of techniques used in examining distributional issues, specifically in evaluating wage differentials between sub- groups (and more generally the impacts of various programs) over the entire range of the earnings distribution. These new techniques were first used to analyze gender earnings gaps (for example, 3