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p-value Calculator

Math Calculators

Z / t / chi-square statistic · one & two tailed · stars

Quick Answer

p-value Calculator: Z / t / chi-square statistic · one & two tailed · stars. p-value Calculator uses standard math formulas to compute accurate results instantly.

Test type

Alternative hypothesis (tails)

p-value
0.049996
Significance：*Reject H₀ at α=0.05
p-value0.049996
Significance stars*
vs α=0.01p ≥ 0.01 not at 1%
Evidence strengthModerate

How p-value works

  1. 1Z-test: two-tailed p = 2·Q(|z|) where Q is the standard normal upper-tail probability; one-tailed p uses Q(z) or Φ(z) directly.
  2. 2t-test: two-tailed p = I_x(ν/2, 1/2) with x = ν/(ν + t²) — the regularized incomplete beta function; one-tailed is half per direction.
  3. 3Chi-square: right-tail p = Q(k/2, χ²/2) — the regularized upper incomplete gamma function. χ² tests are inherently one (right) tailed.
  4. 4Decision rule: compare p with α (commonly 0.05). p < α → reject H₀. Your result: p = 0.049996 (*).

Common critical values (α = 0.05)

TestConditionCritical valuep at this value
Z two-tailedα = 0.051.9599640.0500
Z two-tailedα = 0.012.5758290.0100
t two-tailedν = 202.0859630.0500
t two-tailedν = 122.1788130.0500
χ² right taildf = 13.8414590.0500
χ² right taildf = 1018.3070380.0500
💡 A p-value is P(observing data this extreme | H₀ true) — NOT the probability that H₀ is true. p < 0.05 is a convention, not a law; report the exact p and effect size. One-tailed tests must be justified before seeing data. χ² is always right-tailed.

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How to Use

  1. Enter values or expressions: type directly into the p-value Calculator — keyboard friendly.
  2. Instant results: everything computes live as you type, no button needed.
  3. Follow the steps: the result panel shows full working and formula substitution.
  4. Copy or recompute: one-click copy; change any input to recalculate instantly.

Key Points

  • p-value Calculator is a free online math tool — open and use, no sign-up.
  • All calculations run locally in your browser; your data never leaves the device.
  • Key capability: Z / t / chi-square statistic · one & two tailed · stars.
  • Results come with formulas and reference tables so you can verify every number.

Formula & How It Works

p-value Calculator formula

p-value Calculator uses standard math formulas to compute accurate results instantly.

FAQ

How do I use the p-value Calculator?
Open the page and fill in the input fields — results update automatically. Z / t / chi-square statistic · one & two tailed · stars.
Are the results accurate?
Yes. All calculations use standard mathematical formulas and are verified for accuracy.
Is it free? Do I need to sign up?
Completely free. No registration, login or download required — just open and use.
Does it work on mobile?
Yes. The responsive design works on phones, tablets and desktops.
Is my data saved?
No. All calculations run locally in your browser. Nothing is uploaded or stored.

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Source & Updates

Standard mathematical formulas. All logic verified. Last updated: 2025-07

Last updated:

Formulas and content on this page are reviewed by the YiJianSuan team. For reference only — official sources prevail.

Maintained and periodically reviewed by the YiJianSuan editorial team — review process in ourEditorial Policy.

Cite this page: YiJianSuan. p-value Calculator[EB/OL]. https://www.yijiansuan.com/en/c/math/p-value

Results provided by this tool are for reference only and do not constitute professional advice.