The FORECAST function in Google Sheets is a powerful tool for making predictions based on existing data. By utilizing linear regression techniques, it allows users to estimate future values by extrapolating from historical data points. This function is particularly useful in various fields such as finance, sales forecasting, and scientific research, where understanding trends is essential for informed decision-making.

Syntax

FORECAST(x, data_y, data_x)

• x: The x-value for which you want to predict a corresponding y-value.
• data_y: An array or range of dependent data points (y-values).
• data_x: An array or range of independent data points (x-values) corresponding to the data_y values.

Example #1

FORECAST(10, A1:A5, B1:B5)

This function predicts the y-value when x equals 10, using the dependent values in A1:A5 and independent values in B1:B5. For instance, if data_y holds values {1, 3, 5, 7, 9} and data_x holds values {1, 2, 3, 4, 5}, the result might be 19.

Example #2

FORECAST(15, C1:C5, D1:D5)

This function forecasts the y-value for an x-value of 15, with dependent values in C1:C5 and their corresponding independent values in D1:D5. For example, if C1:C5 contains {2, 4, 6, 8, 10} and D1:D5 contains {1, 3, 5, 7, 9}, the predicted result could be 30.

Example #3

FORECAST(20, E1:E5, F1:F5)

This example estimates the y-value for x equal to 20 using the data range E1:E5 for dependent values and F1:F5 for independent values. If E1:E5 has data {3, 6, 9, 12, 15} and F1:F5 has data {1, 2, 3, 4, 5}, the output may be 45.

Error handling

• VALUE!: This error indicates that the function received a wrong data type, such as text instead of numerical values in the data ranges.
• N/A: This occurs when the function cannot find any valid y-values or x-values within the provided arrays.
• REF!: This error suggests that a reference is invalid, often because the defined range no longer exists.

Conclusion

In summary, the FORECAST function is an invaluable tool within Google Sheets for users seeking to leverage their data for accurate predictions. By understanding the syntax and how to effectively use this function, individuals can enhance their data analysis capabilities, leading to better strategic planning and decision-making.