Maryland consumers believe the national economy is improving, but they're still holding on to their money.

Those, at least, are the latest readings of the Maryland Poll, a consumer survey periodically conducted by the University of Maryland's Division of Behavioral and Social Sciences.

Thirty-four percent of the 501 Maryland residents polled between July 10 and Sept. 12 believed the economy would improve in the next 12 months. About 42 percent of those polled believed their personal finances would improve a year from now.

But 40 percent of the survey subjects said they would wait to buy, when asked: "Do you think that now is a good time to buy the things you want and need, or a good time to wait, or someplace in-between?" Respondents saying that now is a good time to spend accounted for 29 percent. The "in-between" crowd, the cautious optimists who might buy certain big-ticket items, made up 28 percent of the survey total.

John Robinson, director of survey research at the College Park campus, said the results indicate a "very slow, but steady progression . . . in more favorable expectations" among Maryland consumers.

In the winter of 1981 Maryland Poll, 44 percent of the respondents expected the economy to get worse, compared with 29 percent with identical expectations in the latest survey, Johnson said. Also in the newest poll, the proportion of respondents (34 percent) expecting improved economic performance was seven percentage points higher than the proportion (27 percent) expecting continued economic problems.

The survey, using a random sampling of state residents, has a potential 5 percentage-point margin of error.