Qualitative, monitoring categories

Thus, tlie focus of tliis subsection is on qualitative/semiquantitative approaches tliat can yield useful information to decision-makers for a limited resource investment. There are several categories of uncertainties associated with site risk assessments. One is tlie initial selection of substances used to characterize exposures and risk on tlie basis of the sampling data and available toxicity information. Oilier sources of uncertainty are inlierent in tlie toxicity values for each substance used to characterize risk. Additional micertainties are inlierent in tlie exposure assessment for individual substances and individual exposures. These uncertainties are usually driven by uncertainty in tlie chemical monitoring data and tlie models used to estimate exposure concentrations in tlie absence of monitoring data, but can also be driven by population intake parameters. As described earlier, additional micertainties are incorporated in tlie risk assessment when exposures to several substances across multiple patliways are suimned. 

Qualitative methodology uses small samples of subjects and the method of (usually) personal interviews, based on structured or more usually semi-structured questionnaires. The interviews are tape- or video-recorded and then transcribed and analyzed for patterns and categories in students thinking. Data treatment can also be done by commercial packages for qualitative analysis. This methodology provides the possibility for in-depth monitoring and study of students ideas and understandings about scientific concepts. One could think of written questionnaires as instant pictures, and of interviews as motion pictures. 

---