> ## Documentation Index
> Fetch the complete documentation index at: https://docs.agrihub360.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Is a Probe Worth It Here

> Check whether the model is already close enough on a field, or whether a probe would change the numbers.

<Steps>
  <Step title="Open the field, then History">
    The card **Measured against modelled** plots the public model's soil moisture against the nearest measurement over the last two months, with the gap shaded.
  </Step>

  <Step title="Read the verdict">
    On a field with no probe the verdict comes from the nearest COSMOS-UK site. **Keep the model: no probe needed** means the gap is within three points. **Put a probe here** means it is over six. On a field with a probe the card says **Your probe is earning its place**, or that the model would have done.
  </Step>

  <Step title="Act on it">
    **Put a probe here** opens the shop. **Bring a station** opens the bridge for a station you already own. If the verdict is to keep the model, there is nothing to do.
  </Step>
</Steps>

<Frame caption="Measured against modelled on a field with a probe: the verdict, the gap, and the two lines.">
  <img src="https://mintcdn.com/agrihub360/U-w2pyncLxF4g_f2/images/screens/sensor-advisor.jpg?fit=max&auto=format&n=U-w2pyncLxF4g_f2&q=85&s=a6aeb7252adfdb591b183fc7c9f1e6f7" alt="Measured against modelled: the badge 'Your probe is earning its place', 'Mean gap 6.8 points, day to day 10.3', the sentence that the public model runs 6.8 points wetter, and the chart of sensor against model with the gap shaded." width="270" data-path="images/screens/sensor-advisor.jpg" />
</Frame>

## What You See Next

The verdict compares the chart's gap with what the field's decisions can tolerate: five points for drilling, three for irrigation.

## If It Does Not

| You see                             | It means                                      | Do                                                            |
| ----------------------------------- | --------------------------------------------- | ------------------------------------------------------------- |
| No card                             | No measurement within reach, and no probe     | The nearest COSMOS site is too far; the model is all there is |
| The gap changes week to week        | Weather                                       | Read the two-month mean, not the day                          |
| A probe reads wetter than the model | The probe is in a hollow, or the model is dry | Place the probe where the field is typical                    |

Related: [Measured Against Modelled](/features/field-monitoring/measured-against-modelled), [Claim the Sensor](/how-do-i/sensors/claim-the-sensor), [Connect a Station](/how-do-i/sensors/connect-a-station).