Psy 270 Week 6 Paper

Some of the threats to validity include obtaining an ideal sample of individuals in the population of interest. For example, my study question of “What is the association between low levels of vitamin D and depression?” must contain a sample of the representative population that is of geographic interest to the researchers. While a substantial number of persons have low vitamin D levels in the United States (33%), sex, age, race and ethnicity play a role in maintaining healthy vitamin D levels (CDC, 2011). The threat to sample selection would be minimized in the target population if researchers take into account sex, age, race and ethnicity within the population and make a concerted effort to include and assess their serum vitamin D status. This would …show more content…
The role of probability-based sampling method is to minimize bias by assigning a probability value to each individual in the sample. To minimize bias in my study a multiple frames should be used. For example, if I wanted to study vitamin D status in Chicago, different neighborhoods would provide different outcomes. A neighborhood that is predominately African-American or elderly is in all probability likely to have lower circulating vitamin D levels (CDC, 2011). Sampling must be sure to prevent unplanned selectiveness. How would you interpret results from non-probability samples? Describe some of the threats to validity and reliability in data measurement. It would be difficult to determine results from a non-probability sample. Conclusions cannot be drawn about the generalizability of the sample results reflective of the target population because the sample is not representative of the population. A direct threat to external validity would involve an inappropriate sampling frame, such as only sampling persons between the ages of 25-55 when the elderly are likely to be low in vitamin D or isolated and more susceptible to

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