Study Design in Veterinary Diagnostic Evaluation¶
The credibility of any diagnostic claim rests on the study design behind it. This page explains the four study designs Migibio uses — and when each is appropriate.
The Four Designs¶
| Design | Question it answers | Typical setup |
|---|---|---|
| Analytical validation | Is the assay precise and accurate? | Spiked samples, replicates |
| Diagnostic accuracy | Does it detect the disease? | Gold-standard comparison |
| Method comparison | Does it agree with a reference method? | Split samples, two methods |
| Field evaluation | Does it work in the real world? | Multi-site, clinical samples |
Analytical Validation Design¶
Setup: Known-concentration samples (spiked or reference material) run in replicates.
| Parameter | How it is measured |
|---|---|
| LOD/LOQ | Serial dilution to find the detection/quantitation floor |
| Precision (CV%) | 20 replicates within-run and between-run |
| Linearity | Dilution series across the claimed range |
| Interference | Spiking with hemolysate, lipids, bilirubin |
Diagnostic Accuracy Design¶
Setup: Clinical samples tested against a gold standard (e.g., PCR, necropsy, reference lab).
| Metric | Formula | Meaning |
|---|---|---|
| Sensitivity | TP/(TP+FN) | Ability to detect true positives |
| Specificity | TN/(TN+FP) | Ability to avoid false positives |
The gold standard must be independent of the test under evaluation — a study that uses its own assay as the gold standard proves nothing.
Method Comparison Design¶
Setup: The same samples run on the new method and a reference method (e.g., FICT vs ELISA), then compared by Bland-Altman and Passing-Bablok.
Field Evaluation Design¶
Setup: Real clinical samples across multiple sites, evaluating performance under real-world conditions (operator variability, sample quality, time constraints).
FAQ¶
What makes a gold standard valid? It must be independent of the test under study and recognized as definitive for the condition (e.g., PCR for viral DNA, necropsy for pathology).
Why run a field evaluation if analytical validation passed? Analytical validation uses controlled samples; field evaluation confirms the assay still performs with real-world sample quality and operator variability.
For the statistical methods, see Statistical Methods.
Authored by: Migibio Clinical & Scientific Affairs, Guangzhou Magic Biotech Co., Ltd.
Reviewed by: Migibio R&D Quality Committee
Last updated: 2026-08-13
Disclosure: Migibio (Guangzhou Magic Biotech Co., Ltd.) is the manufacturer of the FIA680/FIA880 analyzers and FICT reagents referenced in this content. See our Editorial & Review Policy.