# Growth curve group type

## Plots

The growth curve group type generates two plots based on the following columns:

<table><thead><tr><th width="190">Plot</th><th>Column on x-axis</th><th width="279">Column(s) on y-axis</th></tr></thead><tbody><tr><td>Growth curve</td><td><a href="..#how-calchpi-is-calculated">calcHPI</a></td><td>Cells/mL</td></tr><tr><td>CIZE</td><td><a href="..#how-calchpi-is-calculated">calcHPI</a></td><td>CIZE</td></tr></tbody></table>

## CIZE

{% hint style="warning" %}

## The CIZE metric is an experimental feature

We make [experimental features](https://help.sbtinstruments.com/encyclopedia/software/bactobox-r-software-changelog/experimental-feature) available to everyone to test market interest and gather early\
feedback. [Tell us what you think](mailto:customersupport@sbtinstruments.com?subject=experimental-cize).

Experimental features may change, break, or be removed in future updates.
{% endhint %}

CIZE *(cell-impedance-derived size)* is the average electrical diameter of cells. It is primarily driven by cell size. Other factors may influence CIZE, such as cell morphology and electrical phenotype.

To get a CIZE value, the cells/mL concentration must be above the [limit of detection](https://help.sbtinstruments.com/encyclopedia/measurements-explained/limits-of-detection).

{% hint style="warning" %}

## Known uncertainties about the CIZE metric

It is early days for the CIZE metric. We know that:

* For the same sample, CIZE may change from BactoBox® to BactoBox®
* For the same sample, CIZE may change from flow cell to flow cell
* CIZE may depend on the electrical conductivity of your sample
  {% endhint %}

{% hint style="success" %}

## CIZE best practices

Stick to a single BactoBox® device and a single flow cell. Ensure that the electrical conductivity of your sample is as consistent as possible.

This ensures that you get consistent CIZE results for your sample.
{% endhint %}

## Labels

Use labels to compare growth curves. Each label shows two traces: concentration (solid line) on the primary y-axis and CIZE (dashed line) on the secondary y-axis.

All measurements with an empty *Label* column correspond to the *Unlabelled* trace.

<div data-with-frame="true"><figure><img src="https://4216107837-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FeYTtd7c0A325muFr5lMW%2Fuploads%2FnZA5pDwkTDTgJegUqZF2%2Fimage.png?alt=media&#x26;token=d7c05d8b-0a5d-4624-ae02-e765110f8461" alt=""><figcaption><p>Example growth-curve measurement group. It contains two <em>E. coli</em> growth curves: one in CD medium and one in LB medium. Plots are grouped by label. Concentration (solid line) uses the primary y-axis (left). CIZE (dashed line) uses the secondary y-axis (right).</p></figcaption></figure></div>