Sampling is one of the most difficult and contentious aspects of qualitative research design. There are few guidelines for sampling decisions or for understanding saturation in qualitative family research. The authors frame the problematic of data quality in the selection of units of analysis and observation and consider how to enhance sample richness. They outline considerations for data quant...

In this paper, we propose a nonparametric CUSUM control chart for detecting a range of shifts in the location parameters based on previous research. This control chart is dynamically adaptive, ranks method-based nonparametric and self-starting; it can monitor various sizes of shifts in difference distributions simultaneously; and it can be used to monitor processes at the start-up stages. This ...

Human biomonitoring studies in the Canadian Arctic have measured a wide range of metals and persistent organic pollutants in Aboriginal and non-Aboriginal mothers during two time periods in the Northwest Territories and Nunavut. This analysis provides preliminary estimates on sample sizes and sampling frequencies required to measure significant changes in maternal blood concentrations for PCB 1...

STUDY OBJECTIVE We evaluate the ability of 4 sampling methods to generate representative samples of the emergency department (ED) population. METHODS We analyzed the electronic records of 21,662 consecutive patient visits at an urban, academic ED. From this population, we simulated different models of study recruitment in the ED by using 2 sample sizes (n=200 and n=400) and 4 sampling methods...

For i = 1, ... ,p, let Xi!, ... ,Xini denote independent random samples from normal populations. The ith population has unknown mean Jli and unknown variance a;. We consider the sign testing problem of testing Ho : Jli :::; ai, for some i = 1, ... ,p, versus HI : Jli > ai, for all i = 1, ... ,p, where al,." ,ap are fixed constants. Here, HI might represent p different standards that a product m...

The validity of standard confidence intervals constructed in survey sampling is based on the central limit theorem. For small sample sizes, the central limit theorem may give a poor approximation, resulting in confidence intervals that are misleading. We discuss this issue and propose methods for constructing confidence intervals for the population mean tailored to small sample sizes. We presen...

Five methods for eliciting subjective ratings after each task in a usability test were evaluated. The methods included simple Likert scales as well as a technique derived from Usability Magnitude Estimation. They were tested in a large-scale online study in which participants performed six tasks on an Intranet site. Performance data for the tasks reflected the same pattern as all of the subject...

BACKGROUND While guidance exists for obtaining population size estimates using multiplier methods with respondent-driven sampling surveys, we lack specific guidance for making sample size decisions. OBJECTIVE To guide the design of multiplier method population size estimation studies using respondent-driven sampling surveys to reduce the random error around the estimate obtained. METHODS Th...

which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Kelishadi and her colleagues have done a great job for determining students' high risk behaviors (1) and have published part of this study as percentiles of aminotrans-aminases in Iranian children (2) These data are only from Iran, a country in Middle East and not children...