The Sampling Design and the Data Collection Design

In one line

The sampling design says who will be studied and how they will be chosen, and the data collection design says what will be collected from them, by what instrument, by whom and when.

In the wording a student can write in an exam: the sampling design determines the population, the sampling frame, the sampling unit, the method of selection and the size of the sample, together with the treatment of non-response; the data collection design determines the tools to be used, the items of information to be collected, the manner and sequence of administration, the persons who will collect the data and their training, and the record that will be kept, and both are settled before collection begins and stated in the research methodology.

The sampling design, as a written statement

Six lines, and a student who can write them has a sampling design.

The population, exactly, with place and period.

The sampling frame, and what it omits, chapter 1000.

The sampling unit.

The method, named and justified: simple random, systematic, stratified, cluster or multi-stage, chapter 1010; or one of the non probability methods with the consequences stated, chapter 1020; or a census, chapter 990.

The size, with the reason.

And the treatment of non-response: what will be recorded, and the rule about substitution, which should be that there is none.

Where it goes. Inside the Research Methodology component, chapter 1310.

The data collection design, as a written statement

Seven lines.

The items of information, listed. This is the design decision that determines everything, because an item not on the list will not be collected, chapter 1200's empty tables test.

The tool or tools, chapter 960 and chapter 970.

The instrument itself, drafted and pre-tested, appended.

Who collects, and how they are trained if more than one.

When and where, including times of day, which matters when the respondents work.

The consent procedure, chapter 1400.

And the record: what is kept, in what form, for how long, and where.

Choosing the items of information

The most important step and the least discussed.

Start from the empty tables, chapter 1200. Every cell requires an item.

Add the classification variables. Sex, age group, occupation, settlement, whichever the analysis will break down by. Omitting one of these is the commonest cause of a dissertation that cannot answer its own subsidiary questions.

Add a little redundancy. One or two items that are not strictly required but may prove informative. They are cheap at collection and impossible afterwards.

And add the open closing item. Is there anything I should have asked about, chapter 960.

Then stop. Every additional item costs respondent patience, and a schedule that runs to twenty minutes will be abandoned or answered carelessly.