This unit discusses non-statistical sampling methods, such as haphazard sampling. These techniques involve professional judgment when selecting the sample items. Read the following article,Haphazard Sampling: Selection Biases and the Estimation Consequences of These Biases, which discusses issues related to this approach. What was the purpose of this study? What were their findings?

https://meridian.allenpress.com/cia/article/7/2/P16/208543/Haphazard-Sampling-Selection-Biases-and-the