The first video in Pew Research Center’s Methods 101 series helps explain random sampling – a concept that lies at the heart of all probability-based survey research – and why it’s important. Fresh ...

Non-invasive sampling methods include saliva analysis, hair analysis, urinalysis, and breath testing. <br/>The importance of ...

This paper reports how three field sampling methods performed in different rooms and on different surface types and how they compare using two different metrics of concentration (μg/g) and loading (μg ...

Considerable controversy has taken place between those who favor quota sampling and those who advocate area sampling in opinion polling. This article does not attempt to give a final solution to the ...

Vascular epiphytes are an important component of tropical biodiversity; however, because of problems associated with accessing them, it is hard to obtain a complete species inventory. It is faster and ...

Agricultural soil testing is critical to determining soil’s nutrient concentration and variability across your fields. It is ideal to test your fields’ soil at least every two to three years to inform ...