A (timing control) can be rigorous.Logical formLearned from3 sentences. An off-roading can be rigorous.Logical formLearned from3 sentences. (Math courses) can be rigorous.Logical formLearned from3 sentences. A mastery can be rigorous.Logical formLearned from3 sentences. Observational studies can be rigorous.Logical formLearned from3 sentences. (Inclusion criteria) can be rigorous.Logical formLearned from3 sentences. Spiritual disciplines can be rigorous.Logical formLearned from3 sentences. (Testing systems) can be rigorous.Logical formLearned from3 sentences. A rigorous proof may pertain-to a (power law).Logical formLearned from3 sentences. (Screen tests) can be rigorous.Logical formLearned from3 sentences. A (theoretical foundation) can be rigorous.Logical formLearned from3 sentences. A (language program) can be rigorous.Logical formLearned from3 sentences. A questionnaire can be rigorous.Logical formLearned from3 sentences. A (campus selection process) can be rigorous.Logical formLearned from3 sentences. (Design principles) can be rigorous.Logical formLearned from3 sentences.