Sample size effects, degrees

All drugs will pose some degree of risk, and completed clinical trials are the primary source of information in this subject. Clinical trials do, of course, have limitations. The principal one concerns the everpresent problem of sample size. Rare side effects, if they exist, cannot generally be detected in clinical trials involving limited numbers of patients. Adverse drug reports and case-reports provide early clues to such effects so-called pharmacoepidemiology studies may be mounted to evaluate such risks. 

No reference to size quantization was made in Ref. 54. However, the bandgap is somewhat larger than for a nonquantized sample. The crystal size (ca. 10 nm from both electron microscopy and X-ray diffraction) is a bit large to show size effects in the spectra. In Table 10.4, there is some degree of inconsistency between the various bandgaps and crystal sizes, if it is assumed that size quantization determines the bandgap. It may be that other factors influence the bandgap here. 

The size of the sample to be used depends on the expected water content and the degree of accuracy that is desired. If a high level of accuracy is required, a large sample size should be used to minimize the effect of atmospheric moisture. For titrimetric KF, the United States Pharmacopoeia recommends using a sample that will contain between 10 and 250 mg of water. The minimum amount of water is generally agreed to be 10 mg. 

MRS has been applied in vivo by Kurhanewicz et al.66-61 to provide biochemical and metabolic information from prostate tissue. The metabolic changes centred on citrate, creatine and choline as markers of disease, with a reported sensitivity and specificity of ca. 90% and ca. 83%, respectively. The use of these compounds as diagnostic markers was confirmed on extracts from biopsies, but only small sample sizes have been examined.68 69 Kurhanewicz et al. have developed the in vivo method to a high degree of technical effectiveness, but still the method does not provide the specificity needed for optimal diagnostic clinical use.66-67... 

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