# A to Z of Excel Functions: the CHOOSE Function

17 July 2017

*Welcome back to our regular A to Z of Excel Functions blog. Today we look at the CHOOSE function. *

**The CHOOSE function**

Do you choose to use **CHOOSE**? This function uses **index_num** to return a value from the list of value arguments. **CHOOSE** may be used to select one of up to 254 values based on the index number (**index_num**). For example, if **value1** through **value7** are the days of the week, **CHOOSE** returns one of the days when a number between 1 and 7 is used as **index_num**.

The **CHOOSE **function employs the following syntax to operate:

**CHOOSE(index_num, value1, [value2])**

The **CHOOSE** function has the following arguments:

**index_num:**this is required and is used to specify which value argument is to be selected.**Index_num**must be a number between 1 and 254, or a formula or reference to a cell containing a number between 1 and 254.- if
**index_num**is 1,**CHOOSE**returns**value1**; if it is 2,**CHOOSE**returns**value2**; and so on - if
**index_num**is less than 1 or greater than the number of the last value in the list,**CHOOSE**returns the*#VALUE!*error value - if
**index_num**is a fraction, it is truncated to the lowest integer before being used.

- if
**value1**,**value2**, ...:**value 1**is required, but subsequent values are optional. There may be between 1 and 254 value arguments from which**CHOOSE**selects a value or an action to perform based on**index_num**. The arguments can be numbers, cell references, defined names, formulas, functions, or text.

It should be further noted that:

- If
**index_num**is an array, every value is evaluated when**CHOOSE**is evaluated - The value arguments to
**CHOOSE**can be range references as well as single values.

For example, the formula:

**=SUM(CHOOSE(2,A1:A10,B1:B10,C1:C10))**

evaluates to:

**=SUM(B1:B10)**

which then returns a value based on the values in the range **B1:B10**.

The **CHOOSE** function is evaluated first, returning the reference **B1:B10**. The **SUM **function is then evaluated using **B1:B10**, the result of the **CHOOSE** function, as its argument. A similar idea is also expressed by the formula

**=SUM(A1:CHOOSE(2,A2,A3,A4))**

which will return the result of **=SUM(A1:A3)**.

Certainly it is a function used in modelling, but perhaps it is not used as regularly as some others. This is useful for non-contiguous references:

Just so that we are clear on jargon: a **non-contiguous** range (with reference to Excel) means a range that cannot be highlighted with the mouse alone. In the image above, to highlight the cells coloured you would have to press down the **CTRL** key as well.

**INDEX**, **LOOKUP**, **VLOOKUP** and **HLOOKUP** all require contiguous references. They refer to lists, row vectors, column vectors and / or arrays. **CHOOSE** is different:

**=CHOOSE(index_num, value1, [value2]…)**

As explained above ,this function allows references to different calculations, workbook / worksheet references, *etc*. Try to use the function appropriately. For instance, a well-known Excel website proposes the following formula for calculating the US Thanksgiving date. Assuming cell **A1 **has the year:

**=DATE(A1,11,CHOOSE(WEEKDAY(DATE(A1,11,1)),26,25,24,23,22,28,27))**

To understand this formula, note that **DATE(Year,Month,Day)** returns a date and **WEEKDAY(Date)** returns a number 1 (Sunday) through 7 (Saturday). But doesn’t this formula look horrible? It is full of hard code and it contains an unnecessary number of arguments. The formula could exclude **CHOOSE ***viz*.

**=DATE(A1,11,28-MOD(WEEKDAY(DATE(A1,11,1))+1,7))**

Now let me be clear here. I am not saying this is a simple, transparent formula. Test it. They both provide the same answer. **CHOOSE** – and plenty of additional hard code – has been used unnecessarily.

That’s not to say there isn’t a time and a place for **CHOOSE**. It is useful when you need to refer to cells on different worksheets or in other workbooks. Some argue that it is useful when a calculation needs to be computed using different methods, *e.g.*

**=CHOOSE(index_num, calculation1, calculation2, calculation3, calculation4)**

I disagree. Let me explain. In the example below, I have created a lookup table in cells **E10:E13** which I have called **Data** (I will explain how to create range names later). The calculations are all visible on the worksheet, rather than hidden away in the formula bar. The **index_num **selection, here referred to as **Selection_Number**, is input in cell **E2**. The result?

It’s identical, but easier to follow

**=INDEX(Data,Selection_Number)**

I have taught financial modelling to many gifted analysts over the years and a common mistake made by many is that they build models that are easy to build rather than *models that are easy to understand*. The end user is the customer. It should be simple to use: taking shortcuts invariably only helps the modeller – and even then, more often than not, shortcuts will backfire.

**CHOOSE** can lead to opaque models that need to be rebuilt and are often less flexible to use. You have been warned!

*We’ll continue our A to Z of Excel Functions soon. Keep checking back – there’s a new blog post every other business day.*

*A full page of the function articles can be found here. *