How To Determine Sample Size – Definition & Examples  

How To Determine Sample Size - Definition & Examples  

All set to research your target? Whether you just completed your survey or want to identify the target audience in a specific industry, conducting research can be a great way to understand your audience and tap into the problems they are actually facing. This can also help increase customer loyalty and meet their diverse needs. But before you get into that, how do you determine sample size?  

Moreover, how do you decide who is eligible to fill out your survey, and what should the correct audience number be?  

Remember that sending in too many surveys, regardless of determining the right sample size, can take too much effort and money. However, sending it to just a limited number of people will also not make a dent either.  

Simply put, you should know your sample size before you start circulating your survey. And if you need clarification about how to do that, we are here to help. Read and explore what exactly sample size is and how to determine one.   

How Does Sample Size Work?  

The sample size is a technical term often used to determine the number of samples or individuals you will research. To determine sample size, you must consider several factors like age, demographics, or gender, depending upon your research needs and purpose.  

Also, this size can either be pretty specific or too vague. For instance, if you own a beauty brand and want to research what products are famous in the market, your ideal sample size can be 18-27 aged women who are into self-care. Moreover, your samples must be in a high-temperature area if you sell sunscreens.  

Why Is Determining Sample Size Important?  

When conducting a survey, you may be tempted to reach as many people as you want. However, you can’t just throw your surveys to anyone you want. Sending the surveys to too many people will only exhaust you of time, effort, and money. Sending the survey to a few people will not help you gather meaningful insights.  

This is why determining the right sample size is essential. When you choose the sample size, you reach the correct number of people and gather enough insights simultaneously.  

Factors Affecting Sample Size  

Depending upon your research needs and motives, factors for determining the sample size might vary. However, look at the most basic elements and terms you should know before picking a suitable sample.  

Confidence Level 

When conducting research, confidence level determines your level of confidence toward the accuracy of the research. The more confident you are, the more accurate your data will be.  

Population Size  

Population size is simply the number of people that fit your target demographic. Let’s consider the above example again.  

If you are surveying women in North America, your target audience would be all American women aged 18-27.  

Sounds complicated, right? Remember that your population size need not always be huge.  

Confidence Interval  

Let’s be straightforward. There’s no way that your research is going to be 100% accurate. The confidence interval, also called the margin of error, tells you the degree or level of errors your research might include. You can use margin of error calculators to determine this.  

Standard Deviation  

It’s apparent that survey responses vary from each other. The standard deviation is a metric used in statistical analysis to quantify the spread of a data collection.  

The lesser the standard deviation, the smaller the sample size needed to ensure statistical significance and hence the more accurate results from the survey. But, the required sample size can also be affected by things like the desired accuracy, confidence, and population size.  

Research success hinges on collecting a sample that is statistically and demographically indicative of the community at large.  

RELATED: Calculating Standard Deviation On Excel 

Formula To Determine Sample Size  

Now that you are clear on all significant terms, let’s take a look at how to determine the right sample size.  

Sample Size = (Z-Score)2 * SD * (1-SD) / (margin of error)2 

Here, Z-score = Confidence Level  

SD = Standard Deviation 

Let’s understand the above formula with an example:  

Assuming that your confidence level is 90% with a 0.6 standard deviation and margin of error of +/- 4%, let’s work up your sample size with the formula.  

((1.64)2 x .6(.6)) / (.04)2 

( 2.68x .0.36) / .0016 

.9648 / .0016 


In this case, your sample size is 603. Therefore, your survey should be sent to 603 people to get the right responses.  

Things To Consider When Determining Sample Size  

While determining survey sample size is one of the most common questions most researchers ponder, it is as hard as it seems to calculate. However, before you figure out the size, make sure you have the following things in place:  

Survey Goals & Objectives  

Before you conduct a survey and determine sample size, make sure you know why exactly you are conducting one. Moreover, you must also consider the following questions:  

  • Do you plan on surveying the entire demographic or just a sample population?  
  • Do you want to determine what a specific group thinks about your brand?  
  • Are you simply doing primary market research, or do you plan on making a huge decision based on the outcome?  

Determining the right sample size is vital for surveying a huge population. The size should represent your entire population or target audience collectively.  

RELATED: Setting Survey Goals And Objectives: A Comprehensive Guide 

Precision Level  

Here’s a fact; if you are surveying a considerable population, you are likely to spend a lot. In this case, determining the right sample size can be extremely necessary and essential, so you don’t spend a fortune on anything.  

Note that precision size is the degree of resemblance between your response rate and sample size. The more accurate and exact they are, the more likely you will tap into valuable insights.  

Confidence Level 

When it comes t this, consider your confidence level while calculating the risk involved. Your confidence will directly be in sync with the number of valid responses you get. So if you are highly confident, there is no harm in surveying a colossal population size.  

Summing It Up 

You can use the above formula or online calculators to determine sample size accurately. Here are things you can do to get a higher response rate:  

  • Switch to multiple distribution channels.  
  • Send reminder emails to the respondents to fill out the survey.  
  • Offer incentives like discounts or gifts.  
  • Determine sample size properly.  

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