With the growth in mobile advertising, there is a debate going on between the effectiveness of banners and interstitial ads. However, instead of viewing the ad formats separately, marketers should be looking at how the two complement each other.

Interstitial ads tend to have higher engagement rates and banner ads offer marketers the ability to scale campaigns. Therefore, savvy marketers nowadays are looking for ways to use the ad formats in tandem.

?There shouldn?t be a one-size-fits-all type of approach to mobile advertising,? said Gabi Schindler, chief marketing officer at Amobee, Redwood City, CA.

?For some marketers, a banner ad might be the optimal way for them to get in front of consumers, while others might choose a more immersive experience,? she said.

?Banner ads still play a vital role in the overall marketing mobile mix. An effective static mobile banner ad has to be simple, easy to read and have a distinguishable call-to-action.?

Objective-first
According to Ms. Schindler, marketers have to first establish a campaign?s objective before deciding on a type of ad format to use.

For example, interstitials can be helpful for brand-building while banners are suited towards direct responses at a lower cost.

Because of the more immersive qualities of interstitial ads, they can be used by an advertiser to measure time and interaction spent with an ad unit.

However, if the goal is more oriented towards driving an instant sale, banner ads can be effective at getting consumers to convert.

?A true mobile marketing campaign should be a blend of static banner, rich media, video and potentially 3D ads,? Ms. Schindler said. ?Our advertisers that take this route have found incredible success and results with mobile advertising.?

The case for interstitial
Some experts believe that with a smaller screen size, mobile banner ads do not tap into the full spectrum of mobile advertising opportunities.

Often times, mobile banner ads are essentially shrunken-down versions of desktop campaigns. Marketers are still searching for the right formula that combines interactive elements that grab a consumer?s attention and also use the native features of mobile devices such as touch.

Because interstitial ads are full-screen though, the trick is finding a way to slide them into relevant content when they will not annoy users.

For instance, inserting an interstitial ad into a mobile game between levels can be a great way for marketers to incorporate the ad formats because it is a natural break in usage. On the other hand, an interstitial ad in a news app might seem intrusive to users who are looking to quickly read a few articles.

?Full-screen mobile advertising has created an appealing alternative ? a significant opportunity for marketers to deliver an engaging and compelling message through an ad experience that captures 100 percent of a user's attention,? said Kurt Hawks, general manager of Greystripe, San Francisco.

?When you combine that with astounding publisher fill rates, the traditional banner ad is clearly losing ground,? he said.

Greystripe claims that its interstitial ads show post-click conversions that are five times higher than small banner formats.

One part of the higher post-click conversions is from the large amount of accidental clicks that mobile banner ads generate. For instance, Harris Interactive estimates that almost half of clicks on banner ads are accidental.

Creative execution
According to Amy Vale, vice president of global research and strategic communications at Mojiva, New York, crafting a successful banner ad is about finding the balance between the size of the ad unit and the message behind it.

Compared to other forms of mobile advertising, banner ads help marketers scale the channel by reaching a larger group of mobile users.

?With the right creative, they can be very effective in reaching a mass audience and keeping consumers engaged with brands,? Ms. Vale said. ?Let?s not forget that many rich media executions start out as banner ads and then expand into a three-fourths or full-page experience.?

?The size of the ad unit isn't going to change - it is what it is. But where the opportunity lies for both banner and interstitials to change is in the creative execution,? she said.

Similar to other forms of marketing, the key is to keep the creative simple with a clear reason for why consumers should interact with an ad.

New formats
Some mobile experts say that the original appeal of a mobile banner ad to simply direct users to a landing page has worn off.

Depending on the format, banners and interstitial also hold different engagement rates, according to Matevz Klanjsek, chief product officer at Celtra, Cambridge, MA.

For instance, Mr. Klanjsek claims that mobile expandable banners have a 15 percent engagement rate while an interstitial averages a 12 percent engagement rate.

"Banner ads were originally designed for online advertising for a single task of directing users to the advertiser's landing page," Mr. Klanjsek said.

?In the era of smart mobile devices, with radically different user experience and user behavior, this concept is becoming increasingly inappropriate,? he said.

?Publishers want to keep users on their properties and advertisers want to offer a compact, quick and effective experience suited for consumers with short attention span and little time to spend exploring the advertised product. Expandable banners are the first step in this direction, but truly mobile ad formats are yet to emerge.?

Even though interstitial ads can outperform banners, there is still a place for brands to use banner ads.

?The banner gives brands with an opportunity to deliver a consistent presence throughout the user experience,? said Elena Perez, director of marketing at Medialets, New York.

?Integrated in the page, banners allow the user to interact when they're ready to interact,? she said.

?Interstitials, by definition, deliver an interruptive experience that inevitably captures the user's attention. It's a powerful format and as such needs to be delivered sparingly in order to preserve a positive user experience in an app or site.?

Final Take
Lauren Johnson is associate reporter on Mobile Marketer, New York