By Alexei Oreskovic

SAN FRANCISCO (Reuters) - Four out of five Facebook Inc users have never bought a product or service as a result of advertising or comments on the social network site, a Reuters/Ipsos poll shows, the latest sign that much more needs to be done to turn its 900 million customer base into advertising dollars.

The online poll also found that 34 percent of Facebook users surveyed were spending less time on the website than six months ago, whereas only 20 percent were spending more.

The findings underscore investors' worries about Facebook's money-making abilities that have pushed the stock down 29 percent since its initial public offering last month, reducing its market value by $30 billion to roughly $74 billion.

About 44 percent of respondents said the market debut, seen by investors as troubled, has made them less favorable toward Facebook, according to the survey. In the May 31-June 4 poll of 1,032 Americans, 21 percent said they had no Facebook account.

Facebook's 900 million users make it among the most popular online destinations, challenging entrenched Internet players such as Google Inc and Yahoo Inc. Not everyone is convinced the company has figured out how to translate that popularity into a business that can justify its lofty valuation.

Shares of Facebook closed Monday's regular trading session down 3 percent at $26.90.

While the survey did not ask how other forms of advertising affected purchasing behavior, a February study by research firm eMarketer suggested Facebook fared worse than email or direct-mail marketing in terms of influencing consumers' decisions.

"It shows that Facebook has work to do in terms of making its advertising more effective and more relevant to people," eMarketer analyst Debra Williamson said.

Those concerns were exacerbated last month when General Motors Co, the third largest advertiser in the United States, said it would stop paid advertising on Facebook.

Facebook declined to comment in detail on the survey, but referred to case studies of companies such as Nutella, which found that a 15 percent increase in sales was attributable to Facebook, and restaurant chain Applebee's, whose Facebook ads delivered a threefold return on investment.

Measuring the effectiveness of advertising can be tricky, particularly for brand marketing in which the goal is to influence future purchases rather than generate immediate sales.

The success of an ad campaign must be considered in relation to the product, said Steve Hasker, president of Global Media Products and Advertiser Solutions at Nielsen.

"If you are advertising Porsche motor cars and you can get 20 percent of people to make a purchase that's an astonishingly high conversion rate," said Hasker.

"If you are selling instant noodles, maybe it's not," he

WANING ENGAGEMENT

About two out of five people polled by Reuters and Ipsos Public Affairs said they used Facebook every day. Nearly half of the Facebook users polled spent about the same amount of time on the social network as six months ago.

Keeping users coming back is crucial for all social media services, said Gartner analyst Ray Valdes.

"Facebook continuously has the challenge of Facebook fatigue, of the novelty factor wearing off, and therefore they have to introduce new kinds of interaction," said Valdes, citing new features such as the "Timeline" interface and the planned $1 billion acquisition of mobile photo-sharing app Instagram.

The survey provides a look at the trends considered vital to Facebook's future at a time when the company has faced a harsh reception on Wall Street.

Facebook's $16 billion IPO, one the world's largest, made the U.S. company founded by Mark Zuckerberg the first to debut on markets with a capitalization of more than $100 billion.

Its coming out-party, which culminated years of breakneck growth for the social and business phenomenon, was marred by trading glitches on the Nasdaq exchange. A decision to call some financial analysts ahead of the IPO and caution them about weakness in its business during the second quarter has triggered several lawsuits against Facebook and its underwriters.

Forty-six percent of survey respondents said the Facebook IPO had made them less favorable towards investing in the stock market in general.

While Facebook generated $3.7 billion in revenue last year, mostly from ads on its website, sales growth is slowing.

Consumers' increasing use of smartphones to access Facebook has been a drag on the company's revenue. It offers only limited advertising on the mobile version of its site and analysts say the company has yet to figure out the ideal way to make money from mobile users.

Facebook competes for online ads with Google, the world's No. 1 web search engine, which generated roughly $38 billion in revenue last year. Google's search ads, which appear alongside the company's search results, are considered among the most effective means of marketing.

Facebook is still perfecting the effectiveness of its ads, said Gartner's Valdes. But he said he was surprised that the comments posted on the website from Facebook users' friends were also only responsible for 20 percent of users making a purchase.

"Comments and recommendations from friends on Facebook do carry a lot of weight, so I'm surprised by the number," he said.

The most frequent Facebook users are aged 18 to 34, according to the survey, with 60 percent of that group being daily users. Among people aged 55 years and above, 29 percent said they were daily users.

Of the 34 percent spending less time on the social network, their chief reason was that the site was "boring," "not relevant" or "not useful". Privacy concerns ranked third.

The survey has a "credibility interval" of plus or minus 3.5 percentage points.

(Additional reporting by Gerry Shih; Editing by Edwin Chan and Paul Tait)

Also on HuffPost:

Are you over Facebook? Here are some hipper alternatives to try:
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  • Pinterest

    Certainly the hottest new social network, Pinterest doesn't have all the functions and features of Facebook quite yet -- basically, you're just posting photos to your different boards, which you can categorize by interest or hobby or whatever. You can also follow your friends' boards and comment on their pins. And that's it. Pinterest is a simple, visual concept that has a huge, vibrant community of active users. It <a href="http://techcrunch.com/2012/02/07/pinterest-monthly-uniques/" target="_hplink">hit 10 million users faster</a> than any other social network and is now the <a href="http://www.huffingtonpost.com/2012/04/06/pinterest-traffic-growth_n_1408088.html" target="_hplink">third most popular social network</a> in America, trailing only Facebook and Twitter. <br> <br> You can <a href="http://pinterest.com/" target="_hplink">request an invitation to join Pinterest here</a>.

  • Tagged

    Tagged has a remarkably similar arc to Facebook: Also founded in 2004, and also originally tageted at young people, Tagged is now open to everyone and allows you to customize your profile, play games, message friends, post photos, and meet new people. It has more than 300 million users and more than twenty million monthly active users -- not too shabby, and perhaps worth a look if you want a robust Facebook alternative that's not going anywhere. To see what Tagged is all about, check out this video introduction for beginners. You can <a href="http://www.tagged.com/?" target="_hplink">sign up for Tagged here</a>.

  • Path

    Path is one of several new social networks that seeks to improve on Facebook by making the experience more private and personal: Users are limited to 150 friends on the mobile-only service. A user is instructed to only add his or her closest friends, or anyone you'd invite to your birthday party; the average Path user <a href="http://www.nytimes.com/2012/04/15/business/path-familyleaf-and-pair-small-by-design-social-networks.html" target="_hplink">has 40 connections</a>. Path is sort of like a daily online journal that you open to your friends: You can post photos and videos using your smartphone's camera, update your location, share what songs you're listening to and more. Path has been praised for its intimate feeling and clean design. For more on this social network and its mission statement, check out the introductory YouTube video. (Ignore the Thai -- it's in English). <br> <br> You must have an iPhone or Android phone to participate in Path; a BlackBerry app is apparently on its way. Path has about a million active users, per a <em>recent <em>New York Times</em> article</em>.

  • Pair

    Speaking of intimacy: Pair is a social network in which you can only have one connection, as its name implies. Pair is a sharing service for couples (or really good friends, I suppose), available on Android and iPhone. It takes privacy to the extreme: Pair calls itself a "timeline for just the two of you, where you can post cute video messages and photos that no one else will see." Your significant other may be forcing you to join it any day now. On Pair, you can share photos, videos, location, and to-do lists; you can also play Tic-Tac-Toe with one another and draw sketches in real-time. One of the most precious features of Pair is its "thumbprint" feature, on which you and your partner can virtually press your thumbs together. Like Pair as a whole, you will probably either find this adorable or schmaltzy. Path is available for free <a href="http://itunes.apple.com/us/app/pair/id503663173?mt=8" target="_hplink">in iTunes</a> and <a href="https://play.google.com/store/apps/details?id=com.tenthbit.juliet" target="_hplink">the Google Play store</a>.

  • Highlight

    The number of social networks based on your current location, and your proximity to other users of an mobile application, is on the rise. These "social-location-mobile" (SoLoMo) apps dominated the recent South by Southwest festival, and the app that got the most press was Highlight. Highlight is iPhone only, and the mobile app hooks up with your Facebook and notifies you when you are near a friend, or a friend of a friend, or another Highlight user with similar interests. You can view this person's Highlight profile, and if you're intrigued, you can message that person and perhaps make a new friend or connection. Highlight CEO Paul Davison explains the app to Anderson Cooper in the accompanying YouTube video. Highlight is <a href="http://itunes.apple.com/us/app/highlight/id441534409?mt=8" target="_hplink">available for free in iTunes</a>.

  • Circle

    Circle is, like Highlight, an app that tells you who's around you; unlike Highlight, it has a very pleasant design and lots of options for what information you share publicly and who can see you. You sign up for Circle with your Facebook account; the iPhone-only app shows you when Facebook friends are nearby, and also when friends of friends are close. You can choose to toggle on and off public visibility, if you don't want to be visible to friends of friends. Your profile shows your different Facebook networks (your college, high school, hometown, etc.) and you also have a mini-bio with your name, relationship status and interests. All of this can be toggled on and off as well. Circle is available <a href="http://itunes.apple.com/us/app/circle-whos-around-you/id488720081?mt=8" target="_hplink">on iTunes</a>.

  • Kismet

    Another social location app for your iPhone, Kismet shows you who's around and lets you chat with your nearby neighbors; it also allows users to check in on Foursquare and see which other Kismet users are at their location. Kismet boasts a nice map view, which allows you to see a broad view of other Kismet users around you; there's also an invitation feature that allows you to invite your friends and other users to meet up at a certain place and certain time. You can <a href="http://itunes.apple.com/us/app/kismet/id490929215?mt=8" target="_hplink">download Kismet for iPhone here</a>.

  • Ban.jo

    Our final SoLoMo app (and hopefully the last time I will ever have to write "SoLoMo" ever again) is Ban.jo, which differentiates itself by being available for iPhone AND Android AND on the web. Accessibility! Aside from cross-OS availability, Ban.jo is more of the same: See who's currently around you in list or map view, message nearby folks, check in and update LinkedIn, Twitter, Foursquare and Facebook. Ban.jo is also the only one of these apps publicizing the number of users it has: Its press kit claims that Ban.jo has over one million users worldwide in 185 countries. You can download Ban.jo <a href="http://itunes.apple.com/us/app/ban-jo/id417076117" target="_hplink">for the iPhone</a> or <a href="https://play.google.com/store/apps/details?id=com.banjo.android" target="_hplink">for Android</a>; you can also <a href="http://app.ban.jo/?__utma=18700074.216795228.1337200636.1337200636.1337200636.1&__utmb=18700074.4.10.1337200636&__utmc=18700074&__utmx=-&__utmz=18700074.1337200636.1.1.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=(not provided)&__utmv=-&__utmk=204321424" target="_hplink">try it out at Ban.jo's website</a>.

  • Nextdoor

    Nextdoor is a social network for neighbors and neighborhoods. You join with your home address and are immediately placed into a home neighborhood; all of your connections, and all the content you see in your feed, comes from those that live near you. You don't have to make your address visible to your neighbors, but you do have to verify that you live there with Nextdoor in order to use the site. After you join, using Nextdoor is like a mix of browsing Craigslist and using your community bulletin board. You can find out what's happening in your 'hood and get recommendations for different local businesses and services; there's also a classifieds section for buying and selling. You can check out Nextdoor's pitch in the accompanying video. You can <a href="http://nextdoor.com/" target="_hplink">sign up for Nextdoor for free here</a>.

  • Roamz

    A mobile app for Android and iPhone, Roamz brings in information from Twitter, Foursquare, Instagram and Facebook to let you know what cool stuff is happening around you -- "where the locals go," it claims. That's the real draw of Roamz. It's a social network where you can post status updates and photos and also get information about the places nearby. Check out a video for the app -- which its creators call "Social Googles for the Real World" -- on the left. You can download Roamz for <a href="http://itunes.apple.com/us/app/roamz/id459343660?mt=8" target="_hplink">free for iPhone</a> or <a href="https://play.google.com/store/apps/details?id=com.roamz.app&feature=search_result#?t=W251bGwsMSwxLDEsImNvbS5yb2Ftei5hcHAiXQ.." target="_hplink">for Android</a>.