BE VIZ SMART ✹

Much of the data you see in VizTreks come from surveys.

When you conduct a survey, you ask people a set of questions that reveals their actions, habits, and opinions.

But not all surveys give an accurate picture.

A Good Survey

Asks good questions
It focuses on the topic being investigated and doesn’t steer people toward a “correct” answer.

Explains the data collection process
Who paid for the survey?

Who analyzed the data?

How were people’s responses collected?

The answers will tell you if the survey is unbiased and believable.

Uses a large, random sample
It’s not possible to collect data on every person we want to study. Instead, we collect data from a subset, or sample, and use the data to estimate what’s true for the whole population.

The sample size should be big enough to give a true picture. And each person in the population should have an equal chance of being selected for the sample.

If you want to know how much people in the U.S. spend on their cats every year, you shouldn’t limit your sample to 15 people living in San Diego who adopted rescue cats. That wouldn’t
give you an accurate picture of all U.S. cat owners.