SurveyMonkey Office Hours

Sarah Cho, Survey Research Scientist JUNE 9, 2014

Today’s topic: How many people do I need to take my survey?

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Meet Kathy, a teacher and event organizer

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• Organized a conference for teachers and wants to gather feedback on the conference

How many respondents do I need?

Questions to answer before you start surveying

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• Who is your target population?• What is the size of your target population?• How much error are you willing to tolerate?• What type of response rate do you expect?• Are you thinking of breaking the data down by

subgroups?

Who is your target population?

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• Conference attendees • Invited teachers who did not attend

What is the size of your target population?

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• 2500 teachers were invited to the conference - Target population #1: 500 teachers registered and

attended (attendees) - Target population #2: 2000 teachers who were invited

but did not attend (non-attendees)

How much error are you willing to tolerate?

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• Attendees: Make improvements to conference agenda and amenities

• Non-attendees: Improve program quality or relocate conference to improve attendance rate

How much error are you willing to tolerate?

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What type of response rate do you expect?

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• Attendees: 75% • Non-attendees: 25% How many

teachers will take my survey?

What type of response do you expect? Let’s do some math!

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Total sample desired ÷ expected response rate = total invites needed

• Total sample desired: - 220 Attendees - 350 Non-attendees

• Total invites needed: - Attendees: 200 ÷ 0.75 = ~300- Non-attendees: 350 ÷ 0.25 = ~1400

Are you thinking about breaking down the data by subgroups?

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• For non-attendees: geographic area • For conference attendees: Seasoned veterans versus newbies

• 50 % newbies, 50% seasoned veterans • Overall sample size: 220• 110 newbies• 110 seasoned veterans

• 10% newbies, 90% seasoned veterans• Overall sample size: 220• 22 newbies• 198 seasoned veterans

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Questions? Don’t be shy!