what determines a keyword's click-through rate (CTR) in marketing?

You use keywords almost everywhere whether you are consumer, an advertiser or a content publisher. Keywords is one of the major factors that ties all of these different processes together.

A consumer (or a web user) typically uses keywords to search for content, services or products. An advertiser uses (these) keywords to advertise his products or services such that the web users can be optimally matched by search engines and in advertising networks. A content publisher can research and find these keywords in order to create content that can be matched to the search terms.

The Click-Through Rate (or CTR) refers the same thing in all of these contexts. What percentage of the users that sees your ad or content actually clicks on it to pursue it further? We will broadly classify the above mentioned "contexts" into three main categories: Content Creation, Content Consumption and Web Marketing(or Advertising).

Keywords in Advertising or Web Marketing

In a web marketing context, the keywords are the search terms that you bid on. You ads will be shown only to users who have used the same or similar search term when searching on the search engines such as Google.

In the case of display networks, the keywords are matched against the content of the page (in most cases). It is similar to content matching in organic search results.

Keywords in Content Consumption or Search Engines

Here we mainly refer to the organic search results that are displayed on Search Engine Result Pages (SERP). Various search engines have differing algorithms that match the keywords used in the search with the content on the page. Of course this keyword matching is just one of the factors that the SE uses, but is usually the most important.

Keywords in Content Creation

The use of keywords in content creation works a little differently that the previous two scenarios, in that it is kind of a reverse matching process. Ideally, you would do some keyword research to find "appealing" keywords that are appropriate for the content you intend to write. This could be the keywords that fetch the most revenue or garner the most search or any other criteria you might have. You would then use these keywords in the content and optimize for SEO.

It is very unlikely that you are complaining about a high CTR. Also, it is very unlikely that your CTR is low (or high for that matter) because of one single factor. There are several different factors that affect your CTR. And the combination of all those factors is truly unique to your website.

Click-through Rates in Web Marketing

We will primarily talk about Click-Through Rate in Google Adwords as in web marketing, but it is not hard to extrapolate it to other advertising platforms. Most of these factors should remain the same and you will see that most of these factors are inter-dependent as well.

PPC or Pay per Click

The PPC or Pay per Click refers to your bid amount for the keyword. Usually, as you bid higher you tend to show up more and also higher slots on the webpage. The higher the position of the ad, higher the Click-thru Rate. So, in most scenarios you can bid higher for keywords for which you want to have a higher CTR.

Competition

If your keyword has high competition, then it is more likely for you to be outbid by your competitors. This can reduce the CTR by relegating you to lower ad slots on the page.

Network/Location (SERP vs Display Network vs Search Network)

Your ads could be displayed on various networks, such as the search engine result page, display network or the search network. Each of these networks have varying levels of user engagement. This means that your keyword CTR will vary between these networks.

Ad Type and Size

Even with in the same network there are different types of Ads. You can have text ads, image ads, flash ads etc. depending on what your ad network supports. Each of these different types of Ads can have different click-through rates as well. Also, different size ads perform differently and can have different Click-through rates.

Usually an image ad performs better than text ads in most networks.

Ad Position (Both SERP & in Display Network)

As mentioned above, the position of your ad on the page can determine the click-thru rate. Your position might be influenced by other factors such as competition and bid amounts. Usually, the lower the ad position lower the CTR.

Bounce Rate

The bounce rate of your landing page can also affect the CTR. This is an indirect factor rather than a direct one. A higher bounce rate can negatively affect the quality score of your keyword. This can in turn negatively affect the ad position on the page.

Click-through Rates in Organic Search

The difference between the organic search and Adwords is that you do not get to directly specify the keywords that you want to match for in organic search. In Adwords, you explicitly choose the keywords that you want to display your ads and bid on them. In organic search, the keywords are determined by the search engine by parsing your page content.

There are thousands of factors that the search engine (eg. Google) algorithms look for when determining the position for your content in the search page. The use of keywords in the page content is just one of them. However, you can use several SEO techniques to influence your rankings for a particular keyword.

We will just look at some of the implicating factors with respect to the CTR rather than dwell too much on how to write good content.

Competition

Again, competition is a major factor. The competition in this context refers to the amount of similar (page) content from various domains for the particular keyword. In the context of the web marketing above, it referred to the number of advertisers who were using the same keyword to market, while here in refers to the number content creators.

Position on the SERP

Again, the position on the results page matters. The higher the position, you get a higher click-thru rate. This may not exactly be the case across all searches and content, but generally holds true.

Quality of the Landing Page

As with the bounce rate, this is an indirect factor of the CTR. If you have a low quality landing page that generates a lot of bounces, it can negatively impact the page ranking and position on search engine. This low position can then impact the CTR of the webpage.

Bounce Rate

This again is an indirect factor that affects the position on the search engine results page. A low position on the SERP can negatively impact the CTR of your page and domain.

On a slightly broader note, the conversions are probably more important than CTR. Do not sacrifice conversions for CTR, as a rule of thumb. It is important not to get fixated on one factor, but to improve or optimize the overall impact of the campaign.