Another question that is common relates to processed meat products. Once a processed meat product (ham, hot dog, lunchmeat, etc.) package is opened, the product should be good for up to seven days unless another type of date is on the package and has passed. After the seven days, the product should not be consumed.
Primary research is any type of research that you go out and collect yourself. Examples include surveys, interviews, observations, and ethnographic research. A good researcher knows how to use both primary and secondary sources in her writing and to integrate them in a cohesive fashion.
The posting below looks at, as the title suggests, the strengths and limitations of case studies research. It is from Chapter 3, Qualitative Case Study Reseaarch in the book Qualitative Research: A Guide to Design and Implementation by Sharan B. Merriam. Revised and Expanded from Qualitative Research and Case Study Applications in Education.