It's been a rough year across the board for the stock market, but the once high-flying tech sector has been hit particularly hard. The NASDAQ average, which includes many of the more volatile tech stocks, is down about 15% so far this year and roughly 10% on the S&P 500.

As you attempt to recast your portfolio, keep Warren Buffett's advice about value investing in mind. If you can learn to read a company's statistical profile and focus on the key numbers indicating the company's underlying value, you can survive a bear market.

For example, you should always hold a few companies that have established a strong track record of paying out dividends.   Prices will always rise and fall, but once a company established a record of having a reliable yield, it will go to great lengths to keep it going.

Do you have to sacrifice growth potential to get that good yield? Not at all. Consider AT&T (T - Get Report) . Buffett ranked AT&T No. 1 in his own portfolio, TheStreet reported recently.

T Chart T data by YCharts

The current dividend yield of 5.77% is impressive, and the company has a strong track record of maintaining the payout through all kinds of weather. In fact, it has increased its dividend for 31 straight years.

The most recent earnings report, on January 26, met analysts' expectations. From 2009 through 2015, earnings-per-share growth came in between 2% and 3%. The company is an island of stability in today's topsy-turvy market, and yet there is still room for growth.

AT&T has been around a lot longer than the other big players in the telecom business; it was once simply known as "the phone company." But it has recently made some bold moves to expand its business, such as its acquisitions of DirecTV and Mexican wireless properties Iusacell and Nextel Mexico.

The DirecTV deal has enabled the combined company to offer consumers bundles that include video, high-speed broadband and mobile services using all of its sales channels in 2,300 retail stores and thousands of authorized dealers and agents of both companies nationwide.

DirecTV is one of the premier pay TV providers in the United States and Latin America, with a high-quality customer base, a large selection of programming, and the technology needed for delivering and viewing high-quality video. It also has certain exclusive rights, such as the "NFL Sunday Ticket" that allows pigskin fans to see every out-of-market game on TV, laptops or mobile devices.

With its national retail presence, coast-to-coast TV and mobile coverage, and huge broadband footprint, the company is well positioned to dominate not only the telephone market but also video. The stock is a growth-and-income play for long-term investors.

AT&T now is the largest pay-TV provider in the U.S. and the world, providing service to more than 26 million subscribers in the United States and more than 19 million customers in Latin America.

But the company hasn't neglected its core business. Its marketing strategy has created impressive brand loyalty by hammering home the idea that AT&T has the best telecom network.

The venerable company, now based in Dallas, is the type of high-value stock that fund managers go looking for at a time when other sectors turn unpredictable. The stock's price-earnings ratio, based on forward earnings, is quite reasonable at 12.

But won't consumer goods companies get hit hard if the economy slips into a recession later this year, as some analysts think the stock market is forecasting? Actually, the economic fundamentals seem likely to remain strong for some time. Remember the old saying, attributed to economist Paul Samuelson, that "the stock market has predicted nine of the last five recessions."

What about AT&T's rivals in the telecom sector? Verizon has a solid balance sheet and pretty good growth prospects, but its dividend payout of 4.6% is not quite as good. T-Mobile and Sprint have been making inroads in the telecom market against their larger rivals, but they lack AT&T's broad-based market dominance and reliability.

For a value investing strategy, AT&T is the clear choice in this sector.

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This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.