Common types of survey bias (and how to prevent them)

Administering preliminary market research using surveys can save businesses time and resources. However, accurate feedback and insights depend on the surveyor asking unbiased questions that get honest answers. 

While it may seem impossible to avoid biased survey questions, there are ways to order your questions to prevent answer bias. You can also strategically plan to use certain question types to help ensure you’re not adding your own bias to the survey design.

When conducting research, whether gathering data for a political poll or feedback on a new product idea, honest feedback will provide the most accurate data. 

This article will teach you the different types of survey bias and how to reduce bias in a survey.

Survey bias is a deviation of feedback based on certain influences by the surveyor and respondent. Sampling bias certainly plays a part in how unbiased feedback and insights can be. 

Survey biases can negatively affect research results due to limited data and inaccurate analyses. Such inaccuracies are the result of responsive and unresponsive biases. More specifically, the errors in survey results impact data issues, poor strategies and investments, low ROI, dissatisfaction, and inconclusive results. Understand how a little bias can cause big issues. 

Sampling bias occurs when certain people are systematically more likely to be chosen in a sample than others, and this is also known as purposive sampling.

Purposive sampling has its advantages in certain situations, particularly for smaller groups. Yet, when it comes to sampling a larger population, reducing the amount of bias in your surveys is critical for the most accurate insights. 

Related reading: Learn about 4 leading types of bias and how to prevent them from impacting your next survey results.

Response bias is skewed insights from respondents whose answers deviate from their feelings. The response can be a result of many factors.

Speeding through surveys to finish them quickly may result in biased answers. For example, a user may only complete the multiple-choice answers and not the text responses.

Other biases found in responses may result from respondents not disclosing demographic information in a survey. They might not understand the question, or they’re just not comfortable answering. It’s possible that through hasty purposive sampling, the survey might not be relevant to respondents. It could also be the survey structure that encourages a particular answer.

Overall, there are essentially seven types of response bias: 

Related reading: Eliminate question order bias to improve your survey data.

Non-response bias, also termed systemic bias, is when respondents included in a survey don’t respond. It represents a gap within your feedback and insights that will result in inaccurate data.

Non-response bias also represents respondents who participate in a survey but then drop out for any reason. If a high percentage of survey takers are not responding to your survey, you may have to redesign it to ensure they take it.

There are many reasons why a respondent refuses to participate in a survey. It could be personal or have something to do with how the survey is built.

Non-response bias can also result from timing. Give respondents enough time to complete the survey relative to the feedback they're providing. Don't send a transactional survey one or two weeks after the transaction because your respondents won't remember the interaction.

Related reading: Response bias and non-response bias are the two main ways to get biased feedback. Discover five ways to avoid non-response errors.

Survey bias can also affect different types of interview surveys. Group interviews, one-to-one interviews, panel interviews, phone interviews, and online surveys can suffer from biased interviewers.

It’s impossible not to inherently have a biased position on a subject you’re researching, especially if it benefits your business. However, it's still possible to have an unbiased approach to get the most accurate survey results. 

Acquiring the most accurate survey results means understanding different types of biased survey questions.

We'll examine six survey bias examples here: leading questions, loaded questions, double-barreled questions, absolute questions, ambiguous questions, and multiple-answer questions.

With each biased survey question, you’ll see how it can be written unbiasedly.  

Leading questions involve a surveyor inserting their opinion into the question. This bias influences respondents to answer the question in a way the inquiry suggests is correct. Consequently, this response results in skewed data that won’t help your business objective. 

Example:

A good survey question about Company A’s customer service might look like this:

How helpful are the employees at Company A?

A leading question might look like this:

Do you think the customer service at Company A is better than your experience with employees at Company B? 

This question suggests that Company A is better than Company B because the phrasing is too specific. If Company A’s objective is to compare its customer service with a particular company, the question is satisfactory. Having a clear business objective is so important when building a survey. Learn what you need to know about creating good questions for your following survey.

Loaded questions persuade respondents to answer questions a certain way. This type of query is done when surveyors expect too much from respondents. Even with a buyer persona profile, it’s still best to maintain an objective approach to your survey questions. 

Example:

If Company A is a supermarket that also sells pet food, its survey question should be:

Do you currently have a pet where you live, or not?

This question filters out respondents who have pets and those who don’t. In this case, you can implement question logic for respondents who answer yes and no. 

If Company A leads its survey with a question like “What brand of dry food does your dog like?” the surveyor assumes two things: The consumer has a pet, and it’s a dog. This assumption will lead respondents who don’t have a dog to believe the survey is for dog owners instead of supermarket shoppers. Consequently, they’ll exit the survey, leaving you with inconclusive results. 

Related reading: Write smarter survey questions and avoid asking leading and loaded questions.  

Double-barreled questions are two survey questions asked in one. The question persuades the respondent to offer their opinion on two topics, but with only one opportunity to respond. Here is an example of how to avoid double-barreled questions: 

Example:

Suppose a doctor's office is interested in monitoring its customer service. In that case, they may want to assess their patients' opinions about their treatment from when they checked in to any follow-up visits, if applicable. A good survey question for this scenario might look like this:  

Overall, how responsive has our office been to your questions or concerns?

The double-barreled survey question you want to avoid looks something like this:

How responsive was our team during your visit with us, and did someone follow up with you after the appointment?

Wording questions this way will likely result in a one-answer response that doesn’t satisfy the data you’re looking for within that double-barreled query.

Absolute questions require respondents to be 100% certain about the answers they provide in a survey. Such questions may require a yes or no. They will also include words like “always,” “never,” “every,” or “all.” Responses like this clump together assumptions, leading to invalid cataloging that neglects influential variables.  

Example:

Did Product X’s Outdoor Bug Repellent eliminate every mosquito?

The probability of an outdoor repellent getting rid of every mosquito is unlikely. The respondent will most likely answer no. However, the product might reduce the number of mosquitoes within the perimeter of its use. In this scenario, we're missing critical information to help assess the product's effectiveness. A better question could be worded like this:

How satisfied are you with the reliability of Product X?

Providing a selection of answers like this allows respondents to rank the product's effectiveness. This type of ranking will help the researcher analyze how well Product X performs. 

Ambiguous survey questions leave room for interpretation because the wording isn’t clear. The query may be too broad or lacks clarity. The use of abbreviations, acronyms, and terminology also contributes to ambiguous questions. Questions may be vague or particular to the business or industry. Ambiguous questions allow respondents to interpret queries in a way that makes sense to them, resulting in an obscure response.

Example:

A business objective for a certain dentist’s office is to get referrals. One of the questions they might want to ask patients could look like this:

How likely are you to encourage others to visit our office?

An ambiguous question might look like this:

Do you think your friends and colleagues would like us?

Also, avoid asking broad questions that persuade respondents to rephrase the query, so it makes sense to them. Their interpretation might be different from the true intent of your question. 

Multiple-answer survey questions provide a more controlled approach to collecting feedback and insights. However, the challenges include phrasing the options to avoid inconclusive responses. A good practice is to create answers with choices that don’t overlap.

Example:

If you’re trying to get an assessment of a sample population’s annual income, phrase the survey question like this:

How much money did you personally earn last year?

Don’t do this because it makes the ranges unclear to the respondent:

How much money did you personally earn last year?

Providing overlapping answers eliminates choices. A respondent earning $50,000 a year can be categorized into the second and third categories. In the previous example, that respondent belongs in the third category—details like this matter when analyzing feedback and insights. Get more tips about writing good survey questions and use survey templates with pre-written questions.

When surveys are done correctly, they can yield valuable feedback and insights that will help you make better-informed business decisions.

To get the most honest and unbiased feedback from your surveys:

SurveyMonkey offers customizable surveys for any industry to help you achieve any business objective. Select a plan that works for you today.