Statistical analysis insights

Research methodology, statistical best practices, and updates from the GraphHelix team.

May 6, 2026

Visualizing Longitudinal Data: Spaghetti Plots, Lasagna Plots, and Summary Plots for Repeated Measures

How to visualize longitudinal data: spaghetti plots for individual trajectories, lasagna plots for high density, and summary plots with proper error bars.

May 3, 2026

Free Biostatistics Software for Researchers: JASP, jamovi, R, Python, and GraphHelix Compared

Compare free biostatistics software for researchers: JASP, jamovi, R, Python, GraphHelix, and online calculators by analysis type and learning curve.

April 30, 2026

Normality Test Before ANOVA: A Decision Guide for Shapiro-Wilk, Q-Q Plots, and Kruskal-Wallis

Decide when normality matters for ANOVA: Shapiro-Wilk on residuals, Q-Q plot patterns, sample-size rules, and when to switch to Kruskal-Wallis.

April 27, 2026

Publication-Ready Figures in Python: matplotlib Settings for Journal Submission

Configure matplotlib for journal-ready figures: column widths in mm, pinned Helvetica/Arial fonts, vector output, colorblind-safe palettes.

April 24, 2026

Post-Hoc Tests After ANOVA: Tukey HSD vs Bonferroni vs FDR Compared

Compare Tukey HSD, Bonferroni, Holm, and Benjamini-Hochberg FDR for ANOVA post-hoc tests with a worked 10-comparison example and selection guide.

April 21, 2026

Interpreting Cox Proportional Hazards Models: A Complete Worked Example

Worked example of a Cox proportional hazards model: hazard ratios, confidence intervals, Schoenfeld residuals, and a publication-ready write-up.

April 18, 2026

Choosing the Right Statistical Test: A Decision Guide for Experimental Biologists

A four-decision framework for choosing the right statistical test for experimental data: variable type, number of groups, pairing, and assumptions.

April 15, 2026

Error Bars in Scientific Figures: SEM vs SD vs 95% CI and When to Use Each

When to use SD, SEM, or 95% confidence intervals as error bars in scientific figures. Covers formulas, the overlap trap, R and Python code, figure legend conventions, and common reviewer requests.

April 12, 2026

GraphPad Prism Alternatives: What Researchers Actually Use When Licenses Run Out

Side-by-side comparison of GraphPad Prism alternatives for scientific graphing and statistics. Covers R, JASP, Jamovi, Julius AI, Python, and GraphHelix with feature tables and workflow recommendations.

April 9, 2026

Kaplan-Meier Survival Curves in R: ggsurvplot, Log-Rank Tests, and Publication Formatting

Step-by-step guide to creating publication-ready Kaplan-Meier survival curves in R with ggsurvplot. Covers log-rank tests, risk tables, censoring marks, median survival lines, and manuscript reporting conventions.

April 8, 2026

Power Analysis for Animal Studies: Justifying Sample Size for IACUC and Grant Review

Three methods for justifying animal numbers: formal power analysis, resource equation, and pilot study justification. Covers IACUC documentation requirements, ARRIVE 2.0, the 3Rs, and attrition adjustments.

April 6, 2026

Sample Size for Two-Group Comparisons: t-Test Power Analysis Step by Step

Calculate sample size for an independent two-sample t-test. Covers Cohen d conventions, the per-group formula, a quick reference table, worked examples, and common mistakes in power analysis.

April 3, 2026

Sample Size Calculation for Clinical Trials: Power, Alpha, and Effect Size in Practice

Learn how to calculate sample size for clinical trials. Covers the four core parameters - alpha, power, effect size, and variability - with formulas, worked examples, and common pitfalls.

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