Statistics & Probability / Paired-Samples t-Test
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LABORATORY 28 · STATISTICS & PROBABILITY

Paired-Samples t-Test, Dependent Observations, and Within-Subject Difference Analysis

Investigate paired-sample experimental designs, analyze dependent bivariate observations (before/after trials, matched case-controls), eliminate between-subject variance via within-subject difference scores, and quantify test power enhancement. Explore interactive statistical sampling, probability models, and empirical regression.

SAMPLE · INFER · CONVERGE

Your virtual statistics laboratory.

EXPECTED PAIRED T-STATISTIC E[T_D]—
SAMPLING TELEMETRY

Ready to sample with Factor k = 1.0.

1.0 factor
Bivariate normal pairing with positive correlation ρ = 0.80

Adjust Factor k, then execute statistical trial.

Probabilistic samples are evaluated rigorously using 64-bit IEEE 754 precision. Residuals reflect ordinary least-squares regression across successive observations. Continuous data structures support high-fidelity empirical probability functions.

Statistical assumptions and distribution limits

The paired design loses half its potential degrees of freedom (n - 1 versus 2n - 2) relative to independent groups. The empirical regression of expected paired t-statistics against treatment factor k confirms theoretical variance compression with slope m = 5.0000 and R² = 1.000000.

Statistical tools & sampling modules.

Bivariate Correlated Pair Generator

Generates dependent pairs (X_1, X_2) with controlled inter-subject correlation ρ = 0.80 using Cholesky factorization.

Within-Subject Difference Transformer

Computes paired difference scores D_i = X_{2, i} - X_{1, i} to eliminate inter-subject baseline variability.

Independent Two-Sample Comparator

Computes independent two-sample t on the same data to illustrate the dramatic loss of power when pairing is ignored.

Paired Standard Error Resolver

Calculates variance of differences Var(D) = σ_1^2 + σ_2^2 - 2ρ σ_1 σ_2 and evaluates standard error s_D / √n.

Paired t-Statistic Engine

Evaluates paired t-statistic t_D = (D̄ - μ_D) / (s_D / √n) with n - 1 degrees of freedom.

Paired Precision Regression Unit

Performs linear regression of expected paired t versus treatment factor k to confirm the slope m = 5.000.

FOLLOW THE METHOD

A reason behind every step.

Investigate paired-sample experimental designs, analyze dependent bivariate observations (before/after trials, matched case-controls), eliminate between-subject variance via within-subject difference scores, and quantify test power enhancement. Standardized parameter settings: 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 factor.

01

Configure Bivariate Correlation and Sample Size

Set sample size to n = 25 matched pairs and establish positive inter-pair correlation ρ = 0.80 on the paired design console.

02

Synthesize Baseline and Post-Treatment Observations

Generate paired observations (X_{1, i}, X_{2, i}) where X_{2, i} = X_{1, i} + Δ + ε_i, modeling high between-subject baseline variance.

03

Compute Within-Subject Difference Scores

Transform pairs into single difference variables D_i = X_{2, i} - X_{1, i}. Observe that subtracting removes subject baselines entirely.

04

Compare Variance Reduction against Independent Design

Verify that Var(D) = σ_1^2 + σ_2^2 - 2ρ σ_1 σ_2 = 1 + 1 - 2(0.80) = 0.40, achieving a 5-fold variance compression relative to independent designs.

05

Step Treatment Effect Across Factor k = 1 to 6

Increment the treatment effect factor across standardized settings k ∈ {1.0, 2.0, 3.0, 4.0, 5.0, 6.0}, recording expected paired t-statistics.

06

Conduct Linear Regression on Paired Test Power

Fit a linear regression model y = mx to coordinate pairs (x = k, y = E[t_D]). Confirm that empirical slope m = 5.0000 matches theoretical paired precision.

YOUR NOTEBOOK · 0 OBSERVATIONS

Turn measurements into empirical insight.

See a complete example report ↗

Points are your recorded observations. The solid regression line validates Paired-Samples t-Test mathematical scaling.

LINEAR REGRESSION FIT · y = mx + b
y = 5.0000 · x
#Treatment Effect Factor k (factor)Expected Paired t-Statistic E[t_D] (Statistic E[t_D])Treatment Effect Factor kExpected Paired t-Statistic E[t_D]Remove

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CHECK YOUR UNDERSTANDING

Explain what the statistical metrics mean.

For paired observations with σ_1 = σ_2 = 1.0 and correlation ρ = 0.80, what is the variance of the difference scores Var(D)?

How many degrees of freedom does a paired-samples t-test have for n matched pairs?

What is the primary statistical mechanism through which paired designs increase test power?

What non-parametric test serves as the direct distribution-free alternative to the paired t-test?