# TDIST

The `TDIST` function calculates the probability associated with a Student's t-Test. It returns the probability that the difference between two data sets is greater than or equal to a certain value. This function is commonly used in hypothesis testing.

## Usage

Use the `TDIST` formula with the syntax shown below, it has 3 required parameters:

Parameters:
1. x (required):
The value at which to evaluate the t-distribution.
2. degrees_freedom (required):
The degrees of freedom for the t-distribution.
3. tails (required):
The number of tails to use in the distribution. Must be either 1 or 2.

## Examples

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

### Testing the difference between two means

Suppose we want to test whether the mean difference between two sets of data is statistically significant. We can use the `TDIST` function to calculate the probability of observing a difference as extreme or more extreme than the one we observed, assuming that the null hypothesis (that the means are equal) is true.

### Calculating critical values

In hypothesis testing, we often need to find the critical value for a given significance level and degrees of freedom. The `TDIST` function can be used to calculate this value.

### One-tailed vs. two-tailed tests

The `TDIST` function allows you to specify whether you want to perform a one-tailed or two-tailed test. This is important because it affects how the probability is calculated.

## Common Mistakes

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

### Not specifying the number of tails

The `TDIST` function requires the user to specify the number of tails. Failure to do so can result in incorrect results if the default value is not what is desired.

### Using incorrect degrees of freedom

The degrees of freedom parameter is critical to the calculation of the Student's t-distribution. Using an incorrect value can lead to incorrect results.

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

• `TTEST`

The `TTEST` formula is a statistical formula used to determine the probability of two sample means being equal. It is commonly used in hypothesis testing to determine if there is a significant difference between two sets of data. The formula returns the probability value associated with a t-test, which can be used to determine if the null hypothesis should be rejected or not.

• `TINV`

The `TINV` function returns the inverse of the Student's t-distribution for a given probability and degrees of freedom. This function is commonly used in statistical analysis to determine the value of t for a given probability and degrees of freedom.

• `CONFIDENCE`

The `CONFIDENCE` function calculates the confidence value for a population mean. This is often used in statistical analysis to determine the range in which a population mean is likely to fall. The function takes three parameters: the significance level (alpha), the standard deviation of the population (standard_deviation), and the size of the population (pop_size).

• `STDEV`

The `STDEV` function calculates the standard deviation of a set of numbers. It measures the amount of variation or dispersion of a set of values from the average (mean) value. It is commonly used in statistics to determine the spread of a data set. The values can be supplied as individual cells, ranges, or constants.

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