Models have been categorized based on the object of evaluation and method. In addition, classification is also based on the various other factors that influence the evaluation and its outcomes.For example, the position of evaluator – external or internal- with reference to the organization, extent of stakeholder participation, the purpose of evaluation, the nature of the object evaluated are some of the criteria that have a huge say in the choice of the model (Davidson, 2005). For example, in many cases, accountability and the pressure to document and provide evidence require evaluation, during which an independent evaluation is possible. On the other hand, a more participatory model is likely when the focus is on developing a learning organization (Davidson, 2005). For instance, Razik and Swanson (2001) have given a categorization of models under five groups: goal attainment, judgmental, decision facilitation, naturalistic and self-evaluation models.Models that are feasible to be used in performance appraisal evaluations like teacher evaluation is an example of purpose-based classification. Kein and Aikinss model uses an objective-based approach in teacher evaluation (Razik and Swanson, 2001). Yet another, but popular purpose-based classifications of key models have been done by Preskill and Russ-Eft (2005). Further to these, evaluation models are categorized based on the methods of data collection they employ. they could be qualitative, quantitative or a mixed-method (Guskey, 2000). Quantitative approaches employ statistical analysis tools and are more technical. The tools for data collection, in this case, give tangible data for quantitative analysis. On the other hand, qualitative approaches employ tools such as focus groups, interviews, etc. which provide intangible data that help in qualitative analysis. There are individual methodologies based on specific approaches and over a period, integrated methodologies have come to be developed.