{"id":205970,"date":"2020-10-02T16:12:38","date_gmt":"2020-10-02T14:12:38","guid":{"rendered":"https:\/\/www.scribbr.nl\/?p=205970"},"modified":"2022-08-19T01:25:46","modified_gmt":"2022-08-18T23:25:46","slug":"systematic-sampling","status":"publish","type":"post","link":"https:\/\/www.scribbr.com\/methodology\/systematic-sampling\/","title":{"rendered":"Systematic Sampling | A Step-by-Step Guide with Examples"},"content":{"rendered":"

Systematic sampling <\/strong>is a probability sampling method<\/a> in which researchers select members of the population at a regular interval (or k<\/em>) determined in advance.<\/p>\n

If the population order is random or random-like (e.g., alphabetical), then this method will give you a representative sample that can be used to draw conclusions about the population.<\/p>\n

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When to use systematic sampling<\/h2>\n

Systematic sampling is a method that imitates many of the randomization benefits of simple random sampling<\/a>, but is slightly easier to conduct.<\/p>\n

You can use systematic sampling with a list of the entire population, as in simple random sampling<\/a>. However, unlike with simple random sampling, you can also use this method when you’re unable to access a list of your population in advance.<\/p>\n

Order of the population<\/h3>\n

When using systematic sampling with a population list, it\u2019s essential to consider the order in which your population is listed to ensure that your sample is valid.<\/p>\n

If your population is in ascending or descending order, using systematic sampling should still give you a fairly representative sample, as it will include participants from both the bottom and top ends of the population.<\/p>\n

For example, if you are sampling from a list of individuals ordered by age, systematic sampling will result in a population drawn from the entire age spectrum. If you instead used simple random sampling, it is possible (although unlikely) that you would end up with only younger or older individuals.<\/p>\n

You should not<\/strong> use systematic sampling if your population is ordered cyclically or periodically, as your resulting sample cannot be guaranteed to be representative.<\/p>\n

Example: Alternating list<\/figcaption>Your population list alternates between men (on the even numbers) and women (on the odd numbers). You choose to sample every tenth individual, which will therefore result in only men being included in your sample. This would obviously be unrepresentative of the population.<\/figure>\n
Example: Cyclically ordered list<\/figcaption>You are sampling from a population list of approximately 1000 hospital patients. The list is divided into 50 departments of around 20 patients each. Within each department, the list is ordered by age, from youngest to oldest. This results in a list of 20 repeated age cycles.<\/p>\n

If you sample every 20th individual, because each department is ordered by age, your population will consist of the oldest person in each one. This will most likely not provide a representative sample of the entire hospital population.<\/figure>\n

Systematic sampling without a population list<\/h3>\n

You can use systematic sampling to imitate the randomization of simple random sampling<\/a> when you don’t have access to a full list of the population in advance.<\/p>\n

Research example<\/figcaption>You run a department store and are interested in how you can improve the store experience for your customers. To investigate this question, you ask an employee to stand by the store entrance and survey every 20th visitor who leaves, every day for a week.<\/p>\n

Although you do not necessarily have a list of all your customers ahead of time, this method should still provide you with a representative sample of your customers since their order of exit is essentially random.<\/figure>\n

Step 1: Define your population<\/h2>\n

Like other methods of sampling, you must decide upon the population that you are studying.<\/p>\n

In systematic sampling, you have two choices for data collection:<\/p>\n