Question 426034
looks like systemic sampling to me.


here's some information regarding systemic sampling.


<a href = "http://www.experiment-resources.com/systematic-sampling.html" target = "_blank">http://www.experiment-resources.com/systematic-sampling.html</a>


the choices don't discuss the random generating of the first sample and the random generating of the systemic interval between samples, but the concept is the same minus the details.