Sampling issues in international assessments

Sampling poses interesting challenges in international comparative assessments. Past studies have been often criticised over sampling matters. Samples may not be representative, significant exclusions of low achievers are suspected, samples may not be random, low participation rates have biassed the results, and so on. Notwithstanding these attacks, one major issue in sampling remains the acceptance, application and reporting of strict criteria that would quantify the quality of the samples. Sampling also raises issues in defining target populations. Often, debate over target population definitions gets obscured by the desire to use simpler data collection procedures, potentially jeopardizing the quality of the resulting samples. Of equal concern in an international context is the need for more rigorous sampling methods and procedures.