I am talking about what affinity index is. Why is it needed, how to calculate it and whether it is worth focusing only on the affinity index when promoting your project.

## Determination of the affinity index

Affinity Index (index of compliance, Aff, affinity index, affinity) is an indicator used in marketing as a measure of the ratio between the rating of a media product by the target audience and the rating by the base audience.

Simply put, the compliance index tells you how high-quality the selected advertising platform is. Also, experts use this indicator as a method for determining the profile of a resource where advertising is planned to be placed, i.e. how suitable it is for advertising a product targeted to a specific target audience.

This tool was borrowed from medicine, where a similar mechanism was used to establish the relationship between disease outcome and risk factors.

## Why is an affinity index needed?

The Matching Index helps the advertiser build a campaign to promote their product as efficiently as possible. Choose exactly the channel of communication with the client that will attract the greatest profit. This is done precisely by finding a discrepancy between the desires of the base and target audiences.

Experts cite a consumer survey as an example. Let’s say an entrepreneur decided to find out whether people want to buy his product and from which category these people are (their occupation). The data obtained will not give a correct picture, because some activities are rare and do not reflect the actual interest in the product.

Therefore, it is always necessary to find out the ratio of those who really want to make a purchase and those who do not plan to do so, and use the affinity index formula to draw conclusions about whether or not it is worth targeting the selected audience when selling.

## Application of the index in practice

The affinity index is used in various marketing areas.

The most obvious option is the choice of advertising sites. When a business chooses a media or platform to promote its product or service, it focuses on the matching index. For example, you want to promote your service to young people who are passionate about science. SciOne-style YouTube channels are a good choice because they have a relatively young audience and related topics. Advertising on such resources will give more fruit than advertising on the radio or in a newspaper, where the target audience does not live at all.

This helps entrepreneurs make the right decisions in terms of promoting their projects. For example, if you have a site that fans of Apple technology visit most often, then you should promote it among these people.

Also, marketers use the affinity index in their research and form databases with information about consumers, grouping them according to various criteria.

## The formula for calculating the index of conformity

Now let’s move on to calculating the affinity index in order to find out how suitable the chosen advertising channel or target audience is for us.

To calculate the match index, the following formula is used:

**Rating by target audience / rating by basic audience * 100**

This is a basic formula that you can apply in any way you like by substituting the necessary values in the denominators, for example, age-related audience characteristics. If you are only interested in 50+ clients, then you can divide the number of age clients by the total number of clients for all media considered as an advertising platform. Then the affinity index for each of them will be found out.

It is believed that if the compliance rating is higher than 120, then this is a pronounced sign of quality, that is, the required target audience is more common than usual. If it is between 80 and 120, then the audience is diverse. And if it is less than 80, then this is a low rating, which does not guarantee efficiency.

### Examples of calculating the general formula

Let’s look at a few more examples to make it clearer.

Let’s say you have a social media profile dedicated to nutrition and sales of related products. About 900 women and 400 men are subscribed to it. We take the total number of users and start calculating.

First, let’s calculate the ratio of men to the audience of your profile and the audience of the entire social network. You have 1,300 subscribers, and there are 2,760,000 men in the network of 12,000,000 users, so we think like this:

**((400/1300) / (2,760,000 / 12,000,000)) * 100**

It turns out that the rating for men is 134 units.

Now let’s calculate for women:

**((900/1300) / (9 240 000/12 000 000)) * 100**

It turns out that the rating for women is 89 points.

The rating of men is higher because it is not a specific audience for the social network. But at the same time, many of your subscribers are included in it, and it is worth focusing on it when developing advertising products. You can do the same calculation not for the entire social network, but for channels dedicated to your topic, or for the audience of a particular city, etc.

### Yandex case on the analysis of an audience of expensive cars

In 2018, advertising the Audiences project, Yandex presented a case in which he talked about how the affinity index is calculated in different regions of the Russian Federation.

The hypothesis for the study was the belief that residents of upmarket areas are more interested in premium cars.

Yandex specialists used the formula for calculating the conformity index when analyzing the audience of various settlements. For example, they selected a list of expensive suburban settlements and calculated the number of requests for the names of prestigious cars from these villages. The number of requests from a particular settlement was taken into account in relation to the number of requests from all analyzed settlements.

Yandex analysts compared the performance of the prestigious areas with the usual sleeping areas of Moscow. The calculation was made according to the formula:

**(Number of requests for premium cars in the village / total number of requests in the village) / (number of requests for premium cars in a residential area / total number of requests in a residential area) * 100**

Despite the significant difference in the number of search queries, the match index for a small but prestigious settlement turned out to be higher, as it has a more solvent and interested audience.

### Selection of advertising channels based on the affinity index (radio case)

According to INO Group experts, the use of affinity index as the main metric is not always justified. In particular, this applies to those cases when the total audience significantly exceeds the target.

Let’s say there are two radio stations that you consider as advertising sites. The audience of one consists of 100,000 people, and the other – 1000. At the same time, only 10% are your target audience on the first, and 95% on the second. But this is still less coverage. In addition, a large layer of not yet studied audience is cut off, which will also hear the advertisement and, possibly, convert into customers.

But the affinity index for the second will be higher. And if you thoughtlessly follow only his prompts, then the audience coverage will end up being less, which means that the advertising campaign will be less effective.

Therefore, it is important to take into account other indicators, as well as their mutual influence on each other, when selecting an advertising platform or choosing guidelines for promotion. Only with high-quality full-scale analytics can you achieve maximum results.

## Instead of a conclusion

You can calculate the affinity index both independently and with the help of professionals who can identify the relationship between the affinity index and other indicators. This will most likely be the best choice, because specialized marketers can save time on campaign development and reduce advertising budgets.