Systematic approach, sampling site

Figure 2.6 Stratified systematic sampling or systematic nonaligned sampling. This approach combines random and systematic sampling. The site is divided into regular spaced regions, and then a sample unit is chosen randomly within each of these regions.

Systematic project planning This element ensures that the level of detail required for project planning matches the use of the data being collected, which in turn is determined by the intended end use of the site. Such an approach differs from typical site assessment planning, which often approaches all sites as if they are similar, with standardized sampling strategies (e.g., two soil samples per square meter ), analytical requirements ( test all samples for 36 common contaminants ), and assumed end uses ( all soils will be remediated to residential standards ). 

Two approaches are available. In the first a systematic survey is made of samples from a grid of say 50 m2 at a fixed depth of 50 cm (Fortunati et al., 1994). These samples are inspected and the appropriate parameters measured. The results of this preliminary study act as a guide to further sampling and analysis. With this type of systematic sampling plan the number of samples can easily become unmanageable and their study uneconomic. Furthermore, sampling at a fixed depth will not be useful where the site has been subject to landfill or, as is often the case on industrial sites, has been built up by deposits of fill material itself contaminated. 

This presentation provides an overview of sampling methods and tools suitable to address most site characterizations. The basic sampling types discussed are the systematic, random, and judgmental sampling approaches. 

Accuracy of information Virtual prototypes cannot fully replicate the experience of a physical product (i.e., because one cannot touch them). So, it is possible that customer preferences may be biased. For this reason, it may make sense to continue to use some classical product development approaches to avoid unexpected bias (Kiesler, 1986) generated by Web-based methods. Furthermore, unless the respondents are chosen systematically (instead of randomly based on who visits the firm s web site), there could be further bias due to the population sampled. Hence, effective use of virtual prototyping will require research into understanding the factors that lead to bias and developing methods to manage it. 

---