Prism calculates df correctly, but you can verify manually: df = (R-1)(C-1). For a 3x4 table, df = 23 = 6. If your df is different, check for empty rows/columns.
Even experienced users make mistakes. Here are the top 5 “graphpad verified” fails and fixes.
| Error | Symptom in Prism | Verified Fix | | :--- | :--- | :--- | | Including total row/column | Chi-square astronomically high, unrealistic p | Delete totals. Re-run. | | Using Chi-square when cells <5 | Warning? (Prism doesn’t always warn). P-value unreliable. | Switch to Fisher’s exact test (2x2) or combine categories. | | Wrong table type | “Cannot compute Chi-square” error | Start over with Contingency table (not Column or Grouped). | | Missing values | Zero in a cell that should have a number | Replace with 0 if true; otherwise collect data. | | Not checking expected counts | False positive (Type I error) | Manually view expected counts in results. | chi square graphpad verified
Chi-square test — GraphPad-verified results
To ensure your GraphPad Prism output is valid, you must verify these assumptions: Prism calculates df correctly, but you can verify
GraphPad Prism automatically checks some of these, but you must manually verify others.
Before opening the software, ensure your data fits the criteria for a Chi-Square test: Even experienced users make mistakes
GraphPad Prism is excellent at flagging potential errors.
Imagine you’re comparing two drugs (Drug A vs. Drug B) for headache relief (Yes/No). You have 40 patients.
Performing the test is easy. Verifying it requires diligence. Here is your verification checklist.