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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:

=TDIST(x, degrees_freedom, tails)
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.

Related Formulas

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.

Learn More

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