ISLOGICAL

Tests if a cell contains a logical value, TRUE or FALSE.

Syntax:

ISLOGICAL(value)

Returns TRUE if value is either TRUE or FALSE, and FALSE otherwise.

Example:

ISLOGICAL(D5)

where D5 contains FALSE, returns TRUE, because D5 contains a logical value.

ISLOGICAL(123)

returns FALSE, because 123 is a number, not a logical value.

Application:

Event Registration and Survey

Imagine you are managing an event and want to keep track of attendees and their survey responses. One of the questions on your survey is a simple yes/no question, which you've set up in your spreadsheet to be answered with TRUE or FALSE (boolean values). You need to ensure that the data entered for this question is, in fact, a logical value (TRUE or FALSE) and not text like "yes" or a number like 1.

You can use the ISLOGICAL function to create a validation column that checks the data type and tells you if it's correct.

Table:

	Attendee Name	Survey Question: "Will you attend the next workshop?"	ISLOGICAL Check
	A	B	C
1	Jane Doe	TRUE	TRUE
2	John Smith	FALSE	TRUE
3	Emily White	yes	FALSE
4	David Lee	1	FALSE
5	Sarah Jones	TRUE	TRUE

Explanation:

Jane Doe and John Smith: The values in their cells (TRUE and FALSE) are genuine logical values. The ISLOGICAL function correctly identifies them as such and returns TRUE.
Emily White: The word "yes" is a text string, not a logical value. Even though it's a "yes" answer, the ISLOGICAL function sees it as text and returns FALSE.
David Lee: The number 1 is a numeric value, not a logical value. The ISLOGICAL function returns FALSE.
Sarah Jones: Another correct entry, returning TRUE.

This example shows how ISLOGICAL is a simple but powerful tool for data validation, ensuring that the data you're working with is of the expected type for further calculations or filtering. You could then use this ISLOGICAL column to filter your data to quickly find and correct any entries that were not entered as TRUE or FALSE.