Hawaii’s seasonally adjusted unemployment rate dipped in September to a seven-year low of 3.4 percent as the state’s economy continued to grow. It was the fourth month in a row that the rate has fallen, according to data released Monday by the state Department of Labor and Industrial Relations.

The last time the rate was this low was in March 2008 when it also was 3.4 percent.

“We’ve got a tightening labor market, and the economy is doing pretty well. That pretty much tells it all,” said Leroy Laney, retired professor of economics and finance at Hawaii Pacific University.

The unemployment rate in August was 3.5 percent.

But despite the improvement in the jobless rate, total nonagricultural jobs decreased by 8,100 last month to 634,500 from 642,600 in August. The bulk of that was a decrease of 5,400 positions in government after the state Department of Education hired more people in August than is seasonally typical and hired fewer in September.

Among other areas, the trade, transportation and utilities category had the second-largest decline with 1,600 lost jobs — primarily in retail trade. The education and health services category lost 1,300 jobs with most of the contraction spread out over several subsectors of health services. Construction jobs fell by 600 partly due to inclement weather during the survey week.

Economist Jack Suyderhoud said he and other economists have been worried about the reliability of job numbers in certain sectors.

“There’s a lot of rounding off that goes on with the job number, so we do have some concerns,” said Suyderhoud, a First Hawaiian Bank economics adviser and professor of business economics at the Shidler College of Business at the University of Hawaii. “There’s concern about the reliability about some of the job numbers, but nobody has really found a good explanation why there might be a divergence.”

The unemployment rate and nonfarm payroll numbers are derived from separate surveys. Hawaii’s unemployment rate is derived largely from a monthly telephone survey of households, while a separate survey of businesses determines the number of nonfarm payroll jobs. The nonfarm payroll jobs figure includes people who might hold multiple jobs but doesn’t include people who are self-employed.

Suyderhoud said he prefers to look at trends rather than one-month numbers that can have more volatility.

“The three-month trend is good,” he said. “Employment is always a lagging indicator, but the unemployment rate is certainly consistent with walking around and seeing ‘Help Wanted’ signs all over the place.”

The labor force, which includes people who are employed and people who are unemployed but actively seeking work, jumped by 1,800 last month to 675,050 from 673,250 in August.

There were a record 651,900 people employed last month versus the previous record of 649,500 reached in August, while those unemployed declined to 23,150 from 23,750 over the same period.

Hawaii’s lowest unemployment rate ever was 2.3 percent in October, November and December 2006, and its current 3.4 percent rate is one of the three lowest in the country.

Unemployment rates, meanwhile, rose in all four main Hawaii counties. State and national labor force data are adjusted for seasonal factors, but the county jobs data are not seasonally adjusted and thus do not take into account variations such as the winter holiday and summer vacation seasons.

Honolulu County’s rate rose to 3.4 percent from 3.1 percent, Hawaii County’s rate edged up to 4.3 percent from 4.2 percent, Kauai County’s rate increased to 4.2 percent from 3.8 percent and Maui County’s rate rose to 3.8 percent from 3.4 percent.

Within Maui County, Maui island’s jobless rate rose to 3.6 percent from 3.2 percent while Molokai’s rate fell to 9.0 percent from 9.2 percent and Lanai’s rate decreased to 2.8 percent from 2.9 percent.