# Linear segment \`slope\` seems incorrect in \`get-forecast-outputs\`

**URL:** <https://forum.api.combocurve.com/t/linear-segment-slope-seems-incorrect-in-get-forecast-outputs/476>\
**Category:** Bugs\
**Created:** [August 6, 2026, 7:38pm UTC](https://forum.api.combocurve.com/t/linear-segment-slope-seems-incorrect-in-get-forecast-outputs/476 "2026-08-06T19:38:13Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![josh](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.api.combocurve.com/josh/32/172_2.png) [@josh](https://forum.api.combocurve.com/u/josh)\
**Post date:** [August 6, 2026, 7:38pm UTC](https://forum.api.combocurve.com/t/linear-segment-slope-seems-incorrect-in-get-forecast-outputs/476/1 "2026-08-06T19:38:13Z")

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When I use the get-forecast-outputs endpoint with linear segments, I seem to be getting `-1` or `1` for `slope` but I’d expect to receive the actual slope (matching the UI). It looks like the endpoint currently returns the sign of the slope. Previously I believe this used to return the actual slope so this might be a regression from the previous behavior.

`diEffSec` still seems to be populated correctly, but that may also be omitted in some cases so I can’t rely on that ( [Extremely large decline rates are omitted from `get-forecast-outputs`](https://forum.api.combocurve.com/t/extremely-large-decline-rates-are-omitted-from-get-forecast-outputs/464) ).

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**Author:** ![Danny\_Cooney](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.api.combocurve.com/danny_cooney/32/256_2.png) [@Danny\_Cooney](https://forum.api.combocurve.com/u/Danny_Cooney)\
**Post date:** [August 7, 2026, 7:24pm UTC](https://forum.api.combocurve.com/t/linear-segment-slope-seems-incorrect-in-get-forecast-outputs/476/2 "2026-08-07T19:24:23Z")

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I will send this off to the backend team for context and suggestions.

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**Author:** ![Danny\_Cooney](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.api.combocurve.com/danny_cooney/32/256_2.png) [@Danny\_Cooney](https://forum.api.combocurve.com/u/Danny_Cooney)\
**Post date:** [August 14, 2026, 5:51pm UTC](https://forum.api.combocurve.com/t/linear-segment-slope-seems-incorrect-in-get-forecast-outputs/476/3 "2026-08-14T17:51:13Z")

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Sceduled release August 17,2026.

We’ve added a new field on the Forecast Outputs endpoints so you can read the actual linear slope, not just the direction sign.

Endpoints

GET /v1/projects/{projectId}/forecasts/{forecastId}/outputs  
GET /v1/projects/{projectId}/forecasts/{forecastId}/outputs/{id}  
What changed

Field Meaning When present  
slope (existing)  
Direction only: -1 declining, 0 flat, 1 increasing  
Segments generally  
slopeValue (new)  
Actual linear slope (k), rate change per day (e.g. -0.00137 BBL/D/D)  
Linear segments only  
slope is unchanged, so existing integrations keep working. Use slopeValue when you need the numeric slope shown in the UI.

Where slopeValue lives

It is on each segment object under the phase series (best / p10 / p50 / p90 / ratio):

ForecastOutput  
└── best | p10 | p50 | p90 | ratio  
└── segments  
├── segmentType  
├── startDate / endDate  
├── qStart / qEnd  
├── slope ← direction sign (-1 | 0 | 1)  
├── slopeValue ← NEW: actual linear slope (k); linear only  
└── …  
Example (linear segment)

{  
“best”: {  
“segments”: [  
{  
“segmentType”: “linear”,  
“qStart”: 100,  
“qEnd”: 50,  
“slope”: -1,  
“slopeValue”: -0.00137  
}  
]  
}  
}  
For non-linear segment types (e.g. arps, exp, flat), slopeValue is omitted.

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<div class="post-metadata">

**Author:** ![josh](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.api.combocurve.com/josh/32/172_2.png) [@josh](https://forum.api.combocurve.com/u/josh)\
**Post date:** [August 14, 2026, 6:30pm UTC](https://forum.api.combocurve.com/t/linear-segment-slope-seems-incorrect-in-get-forecast-outputs/476/4 "2026-08-14T18:30:47Z")

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Sounds great, thank you!

Were you able to confirm if the existing slope field always returned the sign only? I can’t say for sure but I believe it used to return the actual slope (what slopeValue will return). In other words I believe there are already integrations relying on the existing slope field to return the slope instead of the sign.

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**Author:** ![Danny\_Cooney](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.api.combocurve.com/danny_cooney/32/256_2.png) [@Danny\_Cooney](https://forum.api.combocurve.com/u/Danny_Cooney)\
**Post date:** [August 14, 2026, 6:49pm UTC](https://forum.api.combocurve.com/t/linear-segment-slope-seems-incorrect-in-get-forecast-outputs/476/5 "2026-08-14T18:49:37Z")

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It was changed in the backend back in October 2025.