ˈiːtʃ ɡɹˈuːpɪŋ kənsˈɪsts ʌv twˈɛnti fˈaɪv pɚsˈɛnt ɔːɹ æz klˈoʊs ˌæzˌɪz mˌæθɪmˈæɾɪkli pɹˈæktɪkəbəl ʌv ˈɔːl mˈɛmbɚ skˈuːlz sˈɔːɹɾᵻd baɪ stˈuːdənt pˌɑːpjʊlˈeɪʃən, ɪŋklˈuːdɪŋ ɐ vɚɹˈaɪəɾi ʌv kɚɹˈɛkʃən fˈæktɚz.
Each grouping consists of 25% (or as close as is mathematically practicable) of all member schools sorted by student population, including a variety of correction factors.