> 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/more/software/what-the-columns-mean.md).
# What the columns mean
What each column shows on the Measurements page and in a measurement group.
The *Measurements* page and each measurement group show your measurements as a table, with one row per program run. Some columns only appear in one of them.
## Columns
| Column | What it shows | You can edit it |
| ------------------------------------------ | -------------------------------------------------------------------------------------------------------------------------------- | --------------- |
| *Status* | Why a run is unusable, for example *Error 3000*. Empty for a usable run. | No |
| *Program* | The program that ran, for example *Measure* or *Clean*. | No |
| *Started at* | When the program started. | No |
| *Sampled at* | When you took the sample from your culture. Access uses it to calculate *calcHPI*. | Yes |
| *ID* | A short ID for the measurement, for example *B72*. | No |
| *HPI* | Hours post-inoculation, if you want to set the time axis yourself. | Yes |
| *calcHPI* | The time axis of the plots, in hours, calculated by Access. See [How Access calculates calcHPI](#how-access-calculates-calchpi). | No |
| *Label* | The name of the culture the sample comes from. Plots draw one line per label. | Yes |
| *Cells/mL* | The concentration of bacterial cells in your sample vial. | No |
| *Total/mL* | The concentration of all particles in your sample vial, cells included. | No |
| *Dilution* | The dilution factor of your sample vial. | Yes |
| *Cells/mL × Dil.* | The cell concentration of your undiluted sample, calculated as *Cells/mL* times *Dilution*. | No |
| *Total/mL × Dil.* | The total concentration of your undiluted sample, calculated as *Total/mL* times *Dilution*. | No |
| [*CIZE*](/more/software/cell-size-cize.md) | The average size of the cells, as the diameter of a sphere with the same volume, in µm. | No |
| *CFU/mL × Dil.* | Your plate count for the undiluted sample. *Correlation* groups use it. | Yes |
| *OD × Dil.* | Your optical density (OD) reading for the undiluted sample. *Correlation* groups use it. | Yes |
| *Measurement group* | The group the measurement belongs to. | Yes |
| *Notes* | Your own notes. | Yes |
After you edit a value, click *Save*. See [Label your samples](/more/software/label-your-samples.md).
## How Access calculates calcHPI
1. If *HPI* has a value, *calcHPI* uses it.
2. If *HPI* is empty, Access calculates *calcHPI* from *Sampled at*. Time zero is the first sample with the same *Label* in the measurement group.
3. If both *HPI* and *Sampled at* are empty, *calcHPI* stays empty.
Time zero is your first sample, not the moment you inoculated your culture. To count from inoculation, take your first sample right after you inoculate. Or enter the hours post-inoculation in the *HPI* column.
Fill in *HPI* for every sample with a label, or for none of them. Your *HPI* counts from inoculation, but a calculated *calcHPI* counts from your first sample. A mix can shift points on the time axis.
## Unusable runs
Access shows unusable runs in faded grey and leaves them out of plots and reports. A run is unusable if it ended with an error, you stopped it, it failed or was abandoned, or you excluded it.
More columns on the Measurements page
Scroll to the right on the *Measurements* page to see these columns.
| Column | What it shows |
| ---------------- | -------------------------------------------------------------------- |
| *Created at* | When the measurement group was created. |
| *Software* | The software version your BactoBox® ran. |
| *Flow cell* | The ID of the flow cell. |
| *Conductivity* | The electrical conductivity of your sample vial. |
| *Classification* | The measurement regime of the run, for example *BacTotal\_v2024-10*. |
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