# regr_slope()

Uses two numerical fields to calculate a trend line, then returns the slope. Use this function to learn more about the relationship between two numerical fields.

```nolang
regr_slope(field_y, field_x)
```

*field_y* is a grouped dependent numeric expression and *field_x* is a grouped independent numeric expression. `regr_slope(field_y, field_x)` uses simple linear regression to calculate the trend line. The input fields (*field_y*, *field_x*) must contain at least two pairs of non-null values. This function works with simple grouped values but not with cogroups.

## Example - Calculate the Relationship Between Number of Activities and Deal Amount

Suppose that you have a dataset that includes the number of activities (such as meetings) and the won opportunity amount.

![Sample scatter plot.](https://a.sfdcstatic.com/developer-website/sfdocs/analytics/media/bi_dev_guide_saql/bi_saql_fn_agg_regint.png)

How much bigger will the deal size be for each extra activity? `regr_slope` performs a linear analysis on your data then calculates the slope (that is, the increased amount you win for each extra activity).

```nolang
q = load "data/sales";
q = group q by all;

--trunc() truncates the result to two decimal places
q = foreach q generate trunc(regr_slope('Amount', 'NumActivities'),2) as 'Gain per Activity';
```

Based on your existing data, every extra activity that you have tends to increase the deal size by $1.45 million, on average.

![Diagram showing slope of a regression line.](https://a.sfdcstatic.com/developer-website/sfdocs/analytics/media/bi_dev_guide_saql/bi_saql_fn_agg_slope.png)

**See Also**

- [regr_intercept()](/docs/analytics/bi-dev-guide-saql/guide/bi-saql-fn-agg-ri.md)
- [Calculate the Slope of the Regression Line](/docs/analytics/bi-dev-guide-saql/guide/bi-saql-examples-stats.md)