Question

The quality control officer at a manufacturing plant needs to determine what percentage of items in a batch are defective. The following are different sampling techniques that could be used by the officer. Classify each as simple random sample, stratified sample, systematic sample, cluster sample, or convenience sample.

A. The officer lists all of the batches in a given month. The number of defective items is counted in randomly selected batches.
B. The officer takes the first 10 batches and counts the number of defective items.
C. The officer groups the batches made in a month into which shift they are made. The number of defective items is counted in randomly selected batches in each shift.
D. The officer chooses every 15th batch off the line and counts the number of defective items in each chosen batch.
E. The officer divides the batches made in a month into which day they were made. Then certain days are picked and every batch made that day is counted to determine the number of defective items.

Answer 1

A. Simple Random Sampling

B. Cluster Sampling

C. Convenience Sampling

D. Systematic Sampling

E. Stratified Sampling

Explanation:

Simple Random Sampling is the sampling when samples are chosen randomly, where each unit has an equal chance of being selected in a sample.

If the population is divided into a different group called cluster and clusters are selected as a sample then it is Cluster Sampling.

In Convenience sampling, observers collect the sample as his\her convenience.

In Systematic Sampling sample is chosen by some criteria like he\she is taken every 10th unit as a sample from the population.

In Stratified Sampling population is divided into several groups such that within the group it is homogeneous and between the group it is heterogeneous. And now a selection of each stratum and unit has an equal chance of selection.