---
title: kaufmansER() function
description: kaufmansER() computes the Kaufman’s Efficiency Ratio (KER) of values in the _value column for each input table.
url: https://docs.influxdata.com/flux/v0/stdlib/universe/kaufmanser/
estimated_tokens: 1274
product: Flux
version: v0
---

# kaufmansER() function

-   Flux 0.40.0+
-   View InfluxDB support

`kaufmansER()` computes the Kaufman’s Efficiency Ratio (KER) of values in the `_value` column for each input table.

Kaufman’s Efficiency Ratio indicator divides the absolute value of the Chande Momentum Oscillator by 100 to return a value between 0 and 1. Higher values represent a more efficient or trending market.

##### Function type signature

```js
(<-tables: stream[A], n: int) => stream[{B with _value: float, _value: float}] where A: Record
```

For more information, see [Function type signatures](/flux/v0/function-type-signatures/).

## Parameters

### n

(Required) Period or number of points to use in the calculation.

### tables

Input data. Default is piped-forward data (`<-`).

## Examples

### Compute the Kaufman’s Efficiency Ratio

```js
import "sampledata"

sampledata.int()
    |> kaufmansER(n: 3)
```

[](#view-example-input-and-output)

View example input and output

#### Input data

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | -2 | t1 |
| 2021-01-01T00:00:10Z | 10 | t1 |
| 2021-01-01T00:00:20Z | 7 | t1 |
| 2021-01-01T00:00:30Z | 17 | t1 |
| 2021-01-01T00:00:40Z | 15 | t1 |
| 2021-01-01T00:00:50Z | 4 | t1 |

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | 19 | t2 |
| 2021-01-01T00:00:10Z | 4 | t2 |
| 2021-01-01T00:00:20Z | -3 | t2 |
| 2021-01-01T00:00:30Z | 19 | t2 |
| 2021-01-01T00:00:40Z | 13 | t2 |
| 2021-01-01T00:00:50Z | 1 | t2 |

#### Output data

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:30Z | 0.76 | t1 |
| 2021-01-01T00:00:40Z | 0.33333333333333337 | t1 |
| 2021-01-01T00:00:50Z | 0.13043478260869565 | t1 |

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:30Z | 0 | t2 |
| 2021-01-01T00:00:40Z | 0.2571428571428572 | t2 |
| 2021-01-01T00:00:50Z | 0.1 | t2 |

#### Related

-   [kaufmansAMA() function](/flux/v0/stdlib/universe/kaufmansama/)
-   [InfluxQL KAUFMANS\_EFFICIENCY\_RATIO()](/influxdb/v1/query_language/functions/#kaufmans-efficiency-ratio)

[transformations](/flux/v0/tags/transformations/)