--- title: "Confidence Interval — Definition & Formula | SpaceForms" description: "A confidence interval is the range within which a true population parameter is expected to fall, at a specified confidence level." lang: en json-ld: | [ { "@context": "https://schema.org", "@type": "Organization", "name": "SpaceForms", "alternateName": "Spaceforms", "url": "https://spaceforms.io", "logo": "https://spaceforms.io/favicon.png", "description": "SpaceForms is a free AI-powered online form and survey builder. 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Typically reported at 95% confidence — meaning if you ran the survey 100 times, the true population value would fall within the interval 95 times. Tighter intervals require larger samples. Always report both the point estimate and the confidence interval. ### Run a Confidence Interval survey free SpaceForms includes pre-built templates with validated wording. Unlimited responses on the free tier — no credit card. [Start free](/free-survey-builder) ## Related terms [ ### Margin of Error Margin of error is the range within which the true population value likely falls, given the sample size and confidence level. ](/glossary/margin-of-error)[ ### Sample Size Sample size is the number of respondents needed for survey results to be statistically meaningful at a given confidence level and margin of error. ](/glossary/sample-size)[ ### Pulse Survey A pulse survey is a short, frequent survey (3-5 questions) used to track sentiment over time. ](/glossary/pulse-survey)[ ### Product-Market Fit Survey (PMF) A PMF survey measures whether a product has achieved product-market fit, typically via Sean Ellis's 'very disappointed' test. ](/glossary/pmf-survey)[ ### Kano Model The Kano model categorizes product features by their impact on customer satisfaction: must-haves, performance, delighters, indifferent, reverse. ](/glossary/kano-model)[ ### Van Westendorp Pricing The Van Westendorp Price Sensitivity Meter uses four questions to identify the range of acceptable prices for a product. ](/glossary/van-westendorp) **SpaceForms** is **The only mainstream survey builder offering unlimited responses on a true free-forever tier.** - Unlimited responses (free) - AI survey in 30s - 36.1% mobile completion - Voice + chat modes SpaceForms Free online form & survey builder. 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