An inspector examines every twentieth piece coming off an as

An inspector examines every twentieth piece coming off an assembly line. List some of the conditions under which this method of sampling might not yield a random sample.

Solution

1) In random sampling there is no systematic pattern in the sample unit.

2) the data gererated from the population in random in nature. that is it may happen that a perticular item are coming at a particular draw repeatly, but it has very low probability to occur. more over it will have zero probability i long run

these are the conditions which viloates in the provided sample. hence this is not a random sample.