In Google Sheets, the CHITEST function is used to calculate the probability associated with a Pearson's chi-squared test on two ranges of data. It helps determine the likelihood that the observed categorical data is drawn from an expected distribution.

Here's a breakdown of each parameter:

"observedrange": This represents the range of observed values or frequencies in the data. It can be a cell range or an array. "expectedrange": This refers to the range of expected values or frequencies based on an expected distribution. It should have the same dimensions as the observed range.

The CHITEST function compares the observed data to the expected data using the Pearson's chi-squared test. It calculates the chi-squared test statistic and determines the probability associated with the test.

This function is commonly used in statistics to assess the significance of relationships between categorical variables or to test if observed data fits an expected distribution. The resulting p-value helps determine whether the observed data significantly deviates from the expected distribution, supporting or refuting the null hypothesis.