To illustrate, the article highlights that there were inaccurate self-reports of egg consumption. Thus, the instrumentation that was used to carry out this study was not accurate enough to measure what it was supposed to. Also, threats of selection bias were introduced into the study, because participants were not randomly selected and the study used health professionals who tend to be more health aware. In addition, the study had threats to external validity specifically in the selection treatment interaction. The study only included Health Professionals, aged 40 to 75 years (1986-1994) and registered nurses who resided in 11 large states, aged 30 to 55 years (1980-1994). Consequently, the results of this study cannot be appropriately generalized beyond the sample that was used to conduct this research. The second study used a non-experimental research design specifically a correlational study to address whether egg yolk intake relates to vascular damage to the carotid plaque area. The dependent variable for this study was carotid plaque area and the independent variables were egg yolk consumption, smoking history (pack-years), and baseline characteristics of the subjects (e.g., age at first visit, systolic pressure (mmHg), diastolic pressure (mmHg), total cholesterol (mmol/L), triglycerides (mmol/L), HDL cholesterol (mmol/L), and
To illustrate, the article highlights that there were inaccurate self-reports of egg consumption. Thus, the instrumentation that was used to carry out this study was not accurate enough to measure what it was supposed to. Also, threats of selection bias were introduced into the study, because participants were not randomly selected and the study used health professionals who tend to be more health aware. In addition, the study had threats to external validity specifically in the selection treatment interaction. The study only included Health Professionals, aged 40 to 75 years (1986-1994) and registered nurses who resided in 11 large states, aged 30 to 55 years (1980-1994). Consequently, the results of this study cannot be appropriately generalized beyond the sample that was used to conduct this research. The second study used a non-experimental research design specifically a correlational study to address whether egg yolk intake relates to vascular damage to the carotid plaque area. The dependent variable for this study was carotid plaque area and the independent variables were egg yolk consumption, smoking history (pack-years), and baseline characteristics of the subjects (e.g., age at first visit, systolic pressure (mmHg), diastolic pressure (mmHg), total cholesterol (mmol/L), triglycerides (mmol/L), HDL cholesterol (mmol/L), and