Читать книгу The Tao of Statistics - Dana K. Keller - Страница 12

 Perceivable

 Describable

 Scores

If you can perceive it, you can measure it. A measurement is an assigned value for a single characteristic. The way a characteristic is captured and, therefore, the way its data should be interpreted determine the measure being used to address the question at hand. Some measures are more accurate than others. Perfect measurement exists only in fantasy; we do the best we can.

Good measurement not only is sufficiently accurate but also places its objects into mutually exclusive categories or scores (or “codes”). Some measures divide people into categories, such as gender. Other measures are more abstract continua, such as perception scales that ask the extent to which a respondent agrees with a statement. Regardless of the type of measurement, sufficient accuracy and mutual exclusivity are needed. The rest of measurement is an extension of those simple concepts.

Data . . . the who, what, where, when, why, and how. Put the pieces together like a jigsaw puzzle, and voilà, you have meaningful information from what was a pile of otherwise useless facts. Be careful: In statistics, as in a jigsaw puzzle, cutting corners and force-fitting pieces can result in a very misleading picture. These shortcuts are sometimes difficult to notice and even more difficult to resolve.

Along with grades, the principal’s school keeps information on standardized test scores, disciplinary actions, health records, extracurricular activities (e.g., clubs), and sporting achievements. Depending on state and federal laws, the principal will have varying levels of access to student records. To try to avoid having to accommodate some of the more sensitive aspects of HIPAA, he tries to avoid using both health and personal information whenever possible in his work.

The director of public health has access to all of the public health and some other state databases. Again, her access is legally limited because the data are about health issues, such as immunizations and outbreaks of certain reported diseases. State and federal laws are quite strict on the access to and use of these types of data.