---
title: variance_y() | variance_x() | Tiger Data Docs
description: Calculate the variance from a two-dimensional statistical aggregate for the dimension specified
---

Since [1.3.0](https://github.com/timescale/timescaledb-toolkit/releases/tag/1.3.0)

Calculate the variance from a two-dimensional statistical aggregate for the given dimension. For example, `variance_y()` calculates the skewness for all the values of the `y` variable, independent of values of the `x` variable.

## Samples

Calculate the variance of a sample containing the integers from 0 to 100:

```
SELECT variance_y(stats_agg(data, data))
FROM generate_series(0, 100) data;
```

```
variance_y
----------
858.5
```

## Arguments

The syntax is:

```
variance_y(
  summary StatsSummary2D,
  [ method TEXT ]
) RETURNS DOUBLE PRECISION
```

```
variance_x(
  summary StatsSummary2D,
    [ method TEXT ]
) RETURNS DOUBLE PRECISION
```

| Name    | Type           | Default  | Required | Description                                                                                                                                        |
| ------- | -------------- | -------- | -------- | -------------------------------------------------------------------------------------------------------------------------------------------------- |
| summary | StatsSummary2D | -        | ✔        | The statistical aggregate produced by a `stats_agg` call                                                                                           |
| method  | TEXT           | `sample` | -        | The method used for calculating the standard deviation. The two options are `population` and `sample`, which can be abbreviated to `pop` or `samp` |

## Returns

| Column   | Type             | Description                                             |
| -------- | ---------------- | ------------------------------------------------------- |
| variance | DOUBLE PRECISION | The variance of the values in the statistical aggregate |