Reliability of data: For the purposes of an evaluation, there should be at least three years of test data with adequate sample sizes and individual student data from previous years. (articles.latimes.com)
We'll be looking at goals, assists, aerial duels, tackles and interceptions, but will be using this season's statistics for Lacazette and Firmino, but the 2013/14 statistics for Daniel Sturridge — the last time there was an adequate sample size for such a comparison to take place. (anfieldindex.com)
We test our hypotheses with data from the European Social Survey (ESS), which includes consistent regional - level identifiers allowing us to match individual and regional information while working with adequate sample sizes. (blog.politics.ox.ac.uk)