# LOGNORMDIST: Excel formulas explained

As a marketer, one of the tools I use frequently is Microsoft Excel. Excel is the backbone of data analytics and helps us better understand our customers, target audience, and product performance. But if you're like me, one of the most daunting aspects of Excel is the seemingly endless array of formulas available in the program. In this article, I'm going to explain one of the most useful formulas in Excel - LOGNORMDIST. First, let's break down what LOGNORMDIST actually means. The formula is used to calculate the cumulative distribution function of a logarithmic normal distribution. Yeah, that's a mouthful. In simpler terms, it helps you analyze and understand data that follows a logarithmic normal distribution pattern. So, why is this formula so useful? Well, it's used in a variety of fields such as finance, biology, and engineering to analyze data sets that don't follow a standard normal distribution (bell curve). Understanding the distribution of your data is crucial to making informed decisions and creating accurate predictions. Now, let's dive into how to actually use the formula in Excel.

## The syntax

=LOGNORMDIST(x, mean, standard_dev, cumulative) The syntax of the formula may seem daunting, but it's actually quite straightforward. The "x" variable refers to the value that you want to find the distribution of. The "mean" is the arithmetic mean of your data set, "standard_dev" is the standard deviation of your data set, and "cumulative" is a logical value (either TRUE or FALSE) that determines the type of distribution you want to find. If "cumulative" is set to TRUE, the formula will return the cumulative distribution function. If it's set to FALSE, it will return the probability density function.

## But how do you use it?

Let's say you have a data set that follows a logarithmic normal distribution and you want to find the probability that a value is less than or equal to a specific number. You could use the LOGNORMDIST formula to find this probability. For example, let's say you're an online retailer and you have data on the amount of money your customers spend on your website. You have found that this data follows a logarithmic normal distribution pattern. You want to know the probability that a customer will spend less than or equal to \$100 on your website. To do this, you would use the LOGNORMDIST formula. Assuming the mean of your data set is 7.5 and the standard deviation is 2.5 (these are just hypothetical numbers for this example), the formula would look like this: =LOGNORMDIST(100, 7.5, 2.5, TRUE) This would give you the cumulative distribution function for the probability that a customer will spend less than or equal to \$100 on your website.

## But wait, there's more!

LOGNORMDIST isn't just limited to finding probabilities of data sets that follow a logarithmic normal distribution pattern. It can also be used in conjunction with other formulas to find even more useful information. For example, you could use LOGNORMDIST with the AVERAGE and STDEV formulas to find the 95th percentile of your data set. This would give you valuable information about the top 5% of your data and help you make strategic decisions.

## In conclusion

Excel can seem intimidating at times, but once you start to understand the power of the formulas available, it becomes an incredibly valuable tool. LOGNORMDIST may seem like a complex formula, but it can provide valuable insights into a data set that follows a logarithmic normal distribution pattern. By using this formula, you'll be able to make more informed decisions and create accurate predictions.