---
title: Module 9. Avoid Strong Positive Tissue Controls
description: "A final point about Calibration is to explain why it is important to avoid selecting strongly positive tissue controls (Figure 11). Strongly positive samples are terrible controls, very insensitive. ![](https://bostoncellstandards.com/wp-content/uploads/2026/09/strongControls-8-14.svg) *Figure 11. Avoid Selecting Strongly Positive Tissue Controls* - Strongly…"
url: "https://bostoncellstandards.com/learning-center/documentation/metric-calibration-tutorial/avoid-strong-positive-tissue-controls/"
updated: "2026-09-01"
category: Metric Calibration Tutorial
tags:
  - Assay
  - IHControl
  - LOD
  - Lower Limit of Detection
  - Report
  - Statistical process Control
---

# Module 9. Avoid Strong Positive Tissue Controls

A final point about Calibration is to explain why it is important to avoid selecting strongly positive tissue controls (Figure 11). Strongly positive samples are terrible controls, very insensitive.

 ![](https://bostoncellstandards.com/wp-content/uploads/2026/09/strongControls-8-14.svg)

*Figure 11. Avoid Selecting Strongly Positive Tissue Controls*

- Strongly positive tissue controls can be misleading. If an assay is beginning to show drift, a control in the plateau range often will not show the change. A control in the dynamic range will have the sensitivity needed to show early changes in an assay.
- If you want to select two controls for an HER2 assay, select one control at the high end of the dynamic range and a second control at the middle of the dynamic range for optimal SPC reporting.