(This is the first in a two-part series on earnings-season results. The second part will focus on the consumer-discretionary sector of the S&P 500, which has had the biggest increase in earnings per share for the third quarter.)

“Quarterly earnings are random events.”

That’s what Ralph Segall said to me in a recent interview. Segall is chief investment officer of Chicago-based Segall Bryant & Hamill, which has about $10 billion in assets under management.

There’s no arguing with that statement because even a stellar company can have a “messy” quarter, with perhaps a one-time asset impairment, cost-cutting write-down, regulatory fine or even a series of events that wipe out profits.

That’s why it’s useful to focus on sales growth when trying to gauge a company’s success over short periods.

If you take a top-down approach to selecting stocks, earnings trends appear, helping you spot sectors and then individual stocks that may be worth your time as you consider where to invest your money.

Read: What stock sectors are saying about the bull market

Earnings season is almost over. Through Tuesday, 456 companies in the S&P 500 Index SPX, -2.37% had reported quarterly results, according to S&P Capital IQ analyst Lindsey Bell. The energy sector dragged down the performance of the index, which is expected by analysts to show a 1.6% decline in third-quarter earnings, compared with growth of 9.2% a year earlier.

Here are estimated EPS growth rates for the third quarter, along with those of the previous four quarters:

S&P 500 Sector EPS growth - Q3 2015 EPS growth - Q2 2015 EPS growth - Q1 2015 EPS growth - Q4 2014 EPS growth - Q3 2014 Consumer Discretionary 16.1% 10.5% 8.5% 13.0% 8.3% Health Care 15.0% 14.7% 21.4% 24.2% 16.2% Telecom. Services 14.6% 11.8% 2.1% 8.7% 8.5% Industrials 5.1% 0.1% 8.7% 12.3% 12.7% Information Technology 4.6% 6.2% 9.1% 17.3% 8.0% Utilities 1.6% 4.5% 0.4% 0.0% 3.8% Financials 1.2% 9.6% 18.3% 4.2% 3.5% Consumer Staples -2.0% 1.7% 4.3% 0.8% 6.0% Materials -14.6% 7.8% -0.7% 1.3% 20.3% Energy -58.6% -55.8% -54.6% -22.0% 11.8% S&P 500 -1.6% 0.1% 3.2% 7.8% 9.2% Source: S&P Capital IQ

Here are EPS growth rates that analysts expect for the fourth quarter, along with the actual growth rates from the fourth quarter of 2014:

S&P 500 Sector Estimated EPS growth - Q4 2015 Actual EPS growth - Q4 2014 Telecom. Services 17.9% 8.7% Consumer Discretionary 9.7% 13.0% Health Care 7.5% 24.2% Financials 3.7% 4.2% Industrials 1.5% 12.3% Utilities -0.4% 0.0% Consumer Staples -3.7% 0.8% Information Technology -4.0% 17.3% Materials -19.3% 1.3% Energy -65.1% -22.0% S&P 500 -3.7% 7.8% Source: S&P Capital IQ

Five sectors are expected to post EPS declines for the fourth quarter. For companies in the consumer-staples and information-technology sectors, the strong dollar, combined with competitive devaluation of currencies by countries with high levels of exports to the U.S., are having a negative effect on sales and earnings, as you can see in almost any earnings press release from an exporter this year.

The manufacturing slowdown in China is damaging the materials sector, while Saudi Arabia’s avowed long-term policy of not cutting oil production, as it normally would when prices decline so much, is hurting U.S. shale oil producers. U.S. oil production is expected to drop considerably during 2016, but it remains to be seen how long it will take for the supply/demand balance to change enough to push prices significantly higher.

Read: Energy stocks, after rebounding from the mini-crash, are still poised for big gains

Telecommunications

The telecommunications sector is expected to fare best. It is dominated by two companies, AT&T Inc. T, -2.24% and Verizon Communications Inc. VZ, -1.52% .

AT&T’s fourth-quarter earnings per share are forecast by analysts to rise by 15% to 63 cents a share from 55 cents a year earlier, reflecting the July acquisition of DirecTV. Analysts expect AT&T’s fourth-quarter sales per share to rise 6% to $6.99. The stock trades for 11.4 times the consensus 2016 earnings estimate, among analysts polled by FactSet. This a low forward price-to-earnings ratio when compared to the ratio of 16.4 for the S&P 500. AT&T’s stock also features a quarterly dividend of 47 cents, for an attractive dividend yield of 5.73%, based on Tuesday’s closing price of $32.79.

Verizon’s fourth-quarter EPS estimate is 88 cents, which would be a 24% increase from 71 cents a year earlier. Sales per share are expected to rise 5% to $7.98. The stock trades for 11.4 times the consensus 2016 EPS estimate and has a quarterly dividend of 56.5 cents, for a yield of 5.01%, based on Tuesday’s closing price of $45.10.

Health care

Looking over the past year, the health-care sector has been strongest, but there’s pressure on the pharmaceutical and biotechnology subsectors. There’s plenty of political pressure over pharmaceutical acquirers raising drug prices and doing everything they can to avoid taxes.

But the questions about revenue accounting by Valeant Pharmaceuticals International Inc. US:VRX for its subsidiary Philador have led to a 65% decline in the company’s share price since Sept. 18.

After Valeant initially said there was no problem with its accounting of relationships with specialty pharmacies, including Philador, the two largest U.S. health-benefits managers stopped doing business with Philador. Then on Oct. 30, Valeant said it was “severing all ties” with Philador.

Philador, in turn, said Nov. 2 that it would cease operations.

You might not expect a problem with one company’s accounting to affect an entire subsector, but Francine McKenna described just how common relationships between large pharmaceutical companies and specialty pharmacies are, and how similar these relationships might be to the one between Valeant and Philador.

To smooth out earnings data, here are the 10 S&P 500 health-care companies with the largest increases in earnings per share for the past 12 months from a year earlier:

We looked at earnings per share, rather than net income, since EPS reflects dilution to the shares if a company has issued stock to fund acquisitions, for executive bonuses or for any other reason. The per-share figures also reflect any reduction in the share counts from buybacks.

Here are sales per share growth figures for the same health-care companies over the past 12 months:

So six of the companies have increased sales and earnings in double digits over the past 12 months. That is, of course, excellent performance. Does looking back like that tell you whether to buy a stock? Of course not. You need to go much further by doing your own research.

Here are full-year EPS and sales per share estimates for the same companies for 2016:

S&P 500 health-care company Estimated EPS - 2016 Estimated EPS - 2015 Estimated 2016 EPS growth Estimated sales per share - 2016 Estimated sales per share - 2015E Estimated growth of sales per share Merck & Co. $3.77 $3.55 6% $14.37 $14.07 2% Gilead Sciences Inc. $11.93 $12.11 -2% $21.69 $22.31 -3% Stryker Corp. $5.61 $5.11 10% $27.88 $26.45 5% Regeneron Pharmaceuticals Inc. $14.66 $12.58 17% $48.60 $39.91 22% Abbott Laboratories $2.39 $2.16 11% $14.46 $13.77 5% Biogen Inc. $18.55 $16.55 12% $50.46 $47.63 6% Quest Diagnostics Inc. $5.11 $4.77 7% $52.89 $52.31 1% Humana Inc. $8.96 $7.75 16% $389.88 $366.47 6% McKesson Corp. $14.45 $12.81 13% $884.41 $836.87 6% Anthem Inc. $10.94 $10.17 8% $319.94 $300.11 7% Source: FactSet

While six of the companies are expected to post double-digit EPS growth next year, only one — Regeneron Pharmaceuticals Inc. REGN, -1.10% — is expected to achieve double-digit growth of sales per share.

Here are analysts’ price targets and forward price-to-earnings ratios for the group:

S&P 500 health-care company Closing price - Oct. 10 Consensus price target Implied 12-month upside potential Share of analysts rating shares ‘buy’ Price/ Consensus 2016 EPS estimate Merck & Co. $54.43 $62.44 15% 42% 14.4 Gilead Sciences Inc. $108.85 $125.65 15% 75% 9.1 Stryker Corp. $97.60 $108.71 11% 64% 17.4 Regeneron Pharmaceuticals Inc. $564.86 $614.25 9% 55% 38.5 Abbott Laboratories $45.76 $50.61 11% 78% 19.2 Biogen Inc. $297.22 $369.69 24% 67% 16.0 Quest Diagnostics Inc. $68.43 $69.50 2% 5% 13.4 Humana Inc. $176.44 $204.73 16% 33% 19.7 McKesson Corp. $184.66 $230.72 25% 95% 12.8 Anthem Inc. $135.27 $176.05 30% 57% 12.4 S&P 500 Health Care Sector 15.9 S&P 500 16.4 Source: FactSet