> For the complete documentation index, see [llms.txt](https://help.sbtinstruments.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.sbtinstruments.com/mpd/workflows/cross-check/cross-check-data.md).

# Cross-check data

It is time to compare data from BactoBox® and CFU methods.\
To do so, we will export the data and do the cross-check in a spreadsheet tool.

<figure><img src="/files/fgue0onNLWJkwdFwynWS" alt=""><figcaption><p>Example of data export from Access to CSV file. The CSV file is opened in a spreadsheet tool such as Excel.</p></figcaption></figure>

We provide a data example for download. Note that the example features both end-of-fermentation cross-check and the full growth curve.

{% file src="/files/E10wZIGIwsBVppdqMctS" %}

## Step by step data analysis

{% stepper %}
{% step %}

### Export CSV file

Use EXPORT CSV in Access to download a file of comma-separated values.

Open the CSV file in a spreadsheet tool like Excel. Save the file as .xlsx.
{% endstep %}

{% step %}

### Calculate arithmetic mean

Use a spreadsheet to calculate the arithmetic mean of the three time points for a given growth medium. In excel the formula would be <kbd>=AVERAGE(number1:number3)</kbd>.
{% endstep %}

{% step %}

### Calculate standard deviation

Use a spreadsheet to calculate the standard deviation of the three time points for a given growth medium. In excel the formula would be <kbd>=STDEV.S(number1:number3)</kbd>.
{% endstep %}

{% step %}

### Plot data

Make a column chart of the arithmetic mean.

Add error bars for standard deviation
{% endstep %}
{% endstepper %}

### Example of harvesting too early

The below column chart is an example of potential premature harvest after 13.5 hours.

The ratio is 1.02 and the error bars are overlapping. This means that BactoBox® and CFU results are practically identical. This corresponds to the cyan region from the introduction [End-of-fermentation cross-check](/mpd/workflows/cross-check.md#cross-check-bactobox-r-and-plate-count-results).

In theory this could mean that you have harvested at the perfect time. But maybe the cell concentration has yet to peak? We will investigate this in a moment in the [Summary](/mpd/workflows/cross-check/summary.md).

<figure><img src="/files/3cdQo1zjOOA8toCB1s1x" alt="" width="124"><figcaption><p>Example of end-of-fermentation cross-check after 13.5 hours where BactoBox ~ CFU . Mean of BactoBox® (lavender) and CFU (yellow) results.</p></figcaption></figure>

### Example of harvesting too late

In the below column chart, the BactoBox/CFU ratio is 6.40 and there is a clear distinction between the error bars. This means that BactoBox® is higher than CFU. This corresponds to the grey region from the introduction [End-of-fermentation cross-check](/mpd/workflows/cross-check.md#cross-check-bactobox-r-and-plate-count-results). It would likely be beneficial to harvest earlier, but let's explore in more detail in the [Summary](/mpd/workflows/cross-check/summary.md) .

<figure><img src="/files/i9MWDcyY6aYd8X6obqER" alt="" width="127"><figcaption><p>Example of end-of-fermentation cross-check after 35.8 hours where BactoBox > CFU . Mean of BactoBox® (lavender) and CFU (yellow) results.</p></figcaption></figure>

## Summary

The CFU and BactoBox® data is now cross-checked. We will wrap up the findings and recommendations for next steps in the [Summary](/mpd/workflows/cross-check/summary.md).


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://help.sbtinstruments.com/mpd/workflows/cross-check/cross-check-data.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.