# LOGEST

The `LOGEST` function returns statistical information on the exponential curve that best fits a given set of data points. It returns an array of values that describe the exponential curve, including the coefficients of determination and standard error. This function is most commonly used in regression analysis to model data points that have an exponential pattern.

## Usage

Use the `LOGEST` formula with the syntax shown below, it has 1 required parameter and 3 optional parameters:

Parameters:
1. known_data_y (required):
An array or range containing the dependent variable data points.
2. known_data_x (optional):
An array or range containing the independent variable data points. If omitted, the values 1, 2, 3, ... are used instead.
3. b (optional):
A boolean value that specifies whether to force the constant term to be equal to 1. If true, the constant term is set to 1. If false or omitted, the constant term is calculated normally.
4. verbose (optional):
A boolean value that specifies whether to return additional statistical information. If true, the function returns additional values including the degrees of freedom, residuals, and so on. If false or omitted, only the coefficients of the exponential curve are returned.

## Examples

Here are a few example use cases that explain how to use the `LOGEST` formula in Google Sheets.

### Predicting future values

If you have a set of data points that follow an exponential curve, you can use `LOGEST` to find the coefficients of that curve. You can then use those coefficients to predict future values for the dependent variable.

### Modeling growth rates

If you have data that represents the growth of a population, a market, or some other system, you can use `LOGEST` to model the growth rate of that system over time. This can help you make predictions about future growth and plan accordingly.

### Analyzing trends

If you have data that shows an exponential trend, you can use `LOGEST` to find the coefficients of that trend. This can help you understand the trend better and make more informed decisions based on it.

## Common Mistakes

`LOGEST` not working? Here are some common mistakes people make when using the `LOGEST` Google Sheets Formula:

### Incorrect number of arguments

One of the most common mistakes is using an incorrect number of arguments with the LOGEST formula. This can cause errors such as #VALUE! or #NUM!. Make sure you are using the correct number of arguments as per the syntax of the formula.

### Incorrect data type

Another common mistake is using the incorrect data type, such as using text instead of numbers. Make sure all data is in the correct format before using the formula.

### Incorrect range references

A mistake that can be made is using incorrect range references for the known_data_y and known_data_x arguments. Make sure the ranges are correct and do not include any extraneous data.

### Incorrect optional arguments

If you use the optional arguments b and verbose, make sure they are used correctly and in the correct order. Incorrect usage of these arguments may cause errors.

### Insufficient data

Finally, one of the most common mistakes is using insufficient data for the known_data_y and known_data_x arguments. Make sure you have enough data points for the formula to work correctly.

The following functions are similar to `LOGEST` or are often used with it in a formula:

• `TREND`

The `TREND` formula is used to calculate future values based on historical data. It fits a straight line (using the method of least squares) to the arrays specified in the `known_data_y` and `known_data_x` parameters and then uses that line to calculate new y-values for the array specified in the `new_data_x` parameter. If `b` is set to TRUE, then the calculation will include the y-intercept of the line. This formula is commonly used in forecasting and trend analysis.

• `FORECAST`

The `FORECAST` function in Google Sheets is a statistical function that predicts a future value along a linear trend. It returns the predicted value for a chosen x value based on the linear regression of a set of known x and y values. This function is commonly used in finance to predict future values.

• `GROWTH`

The `GROWTH` formula in Google Sheets calculates predicted exponential growth by using existing data. It returns an array of values that represent the y-values predicted for the new x-values based on the existing data.

• `LINEST`

The `LINEST` formula is used to calculate the statistics for a line by calculating the line's slope and y-intercept. It is commonly used to find the best-fit straight line for a given set of data points.

You can learn more about the `LOGEST` Google Sheets function on Google Support.