Personal incomes increased one percent in November while housing starts continued strong at an annual rate of 2.1 million units-two further signs the economy will be casting merrily through the Christmas season and into next year.

The new figures, released yesterday by the Commerce Department, followed recent sales and employment numbers which show that U.S. economic activity remains robust despite widespread predictions of a recession.

Housing starts in particular have remained strong despite rising interest rates as home buyers continue to invest their saving in real estate.

November was the ninth month in 1978 that new homes have been built at a rate of over 2 million, the mark of a boom year for the industry. But there was also some indication that homebuilding activity may have finally peaked. New building permits for future home construction dropped 2 percent during the month, and industry officials predicted the bad news is just around the corner.

"I think what we've been seeing is a strong urge by many people to get into the housing market before the end." said Louis Thompson, a spokesman for the National Association of Home Builders. "It's desperation before the tight money squeeze. We do not look at this to be a coninuing trend."

With the cost of home mortgages now averaging more than 10 percent nationwide, and approaching 11 percent in some areas, many industry analysts expect housing activity to begin to trumble early next year, falling as much as 25 percent below its current level.

Total personal income last month stood at $1.78 trillion, an increase of $17.3 billion over October. Though last month's jump was slightly below October's 1.3 percent rise, it was nonetheless encouraging to White House officials because it means more dollars have been available for consumers to spend - particularly Christmas shopping.

The catch, however, is this: The gains haven't been real. Despite the burst in wage and salary scales this year, they have barely been enough to

keep pace with inflation. The Consumer Price Index has been climbing at about the same rate as personal income.

The Commerce Department said factory payrolls alone jumped by one percent, or $5.2 billion, to a total of $313.9 billion. Analysts attributed this increase to higher average hourly earnings and to the addition of more than half a million jobs to the economy last month.

Government wages and salaries rose $1.3 billion to a total $222.3 billion. And farm income increased by $1.4 billion-a 5.1 percent leap-to a total $28.7 billion.