Grocers are suckers for surveys and projections. Supermarket executives can track exactly what the public has been eating and how much the public has been spending. But in an intensely competitive business where continuing high volume is essential to profit, tomorrow's pattern is as important as today's.

Therefore, at least two among the dozen or more surveys offered at the annual Food Marketing Institute here last week are likely to cause some thumb-sucking among those in the industry who expect an era of great change in family living and eating habits.

National studies by Ladies' Home Journal and Women's Day magazines strongly suggest the opposite: That traditional patterns of family life are being followed. Families are dining together. Women continue to do the great majority of the grocery shopping, meal planning and cooking. Traditional foods such as roast beef and cake retain their popularity. And americans seem to be more likely to seek slimness by skipping a meal or dessert with a meal than by adopting special diest.

Among the results: More than 80 percent of those sampled had eaten dinner at home the previous evening, and for nearly 75 percent it had been a family meal. Only 6 percent of the respondents reported that their families ate at home but at different times; yet multiple meals have been considered a major reason for fragmented families and possibly for poor nutrition.

Men, according to the LHJ survey, aren't playing nearly the role that has been claimed for them. Women did 94 percent of the shopping, with the husband going along fairly often but acting as the "primary shopper" only 4 percent of the time. The same percetage of men prepared breakfast, but only 2 percent of dinner preparation "was done by a husband on his own."

Working women may have changed their shopping patterns to fit the twin constraints of less time and (due to inflation) less disposable income. But what draws them to supermarkets hasn't changed very much.

The audience for both magazines is made up of the very women their separate surveys tend to applaud. But even with that caveat, the findings are worthy of attention because they refute a number of trendy assumptions.

The Ladies' Home Journal study, entitled "What's Happening to Mealtime," was compiled from telephone interviews in 19 metropolitan areas across the nation. The smallest was Raleigh, N.C. The largest was New York City. The questioning took the form of "snapshots" of what the person interviewed had done about food preparation and eating the day before.

In addition to the patterns above, the survey indicated that most families still favor beef for dinner, though pasta has shown strong growth as a main-course item. They eat cake more often than ice cream or fruit for dessert, but 40 percent of the households skipped dessert at dinner. (The same percentage - though not necessarily the same households - skipped vegetables, too.) For breakfast, baked goods lead eggs adn cereal; for lunch, sandwiches are most popular.

Only one family in 20 has wine with dinner and even less have beer.

Families with children, as opposed to those who do not have children, consume more waffles, pancakes or French toast at breakfast, more soup at lunch and more hamburgers for dinner.

Demographic breakdowns of the survey show:

Working women shop less frequently than homemakers, skip breakfast more frequently, eat more expensive foods and entertain guests for dinner more often.

High-income families (more than $25,000) not only spend more money for food than low-income families (less than $12,500), they are more likely to plan meals ahead, buy more kitchen gadgets, are less likely to eat three meals a day and the high-income husband is far less likely to do the shopping than is the low-income husband. According to the report, "One in three high-income households spends more than $80 per week compared with one in 100 low-income households.

There are some bad habits among both groups. The average preparation time for breakfast and lunch is 10 minutes for each meal. Dinner preparation averages 35 minutes, with 7 of 10 using some form of convenience food, mostly from a can. Nearly 20 percent said they do no planning, almost 50 percent just cook what's handy and 66 percent don't cook for future meals. Only 40 percent prepare snacks, but 40 percent skip at least one meal.

Women's day, in "Comsumer Attitudes Toward Supermarkets and Their Advertising," offers evidence that "time and money" are causing women's attitudes toward shopping to change. Working woment have less time for comparison shopping, the magazine's study indicates, and are forced to serve what they can afford, thus losing the opportunity for creative menu planning and shopping. Whether they work or not, they tend to shop when their husbands get paid. They will, however, change supermarkets and shop near work or along the route home.

The husband is considered a shopping risk because he may buy "gourment items."

They still tend to rely on newspaper ads and coupons and in fact may buy several copies of a paper just to obtain more coupons. But they are "discriminating" and want coupons that offer substantial savings on products used every day. These and the specials in ads are considered the two biggest draws for women shoppers. (Stampe and games are judged to be "gimmicks" that create the image of a higher priced store.)

In choosing where to shop, the cconsumers sampled give weight to savings on meat and other products; the image created by pricing, cleanliness, lighting, aisle width and layout; speed of checkout; store personnel attitude, and an "appearance of freshness" in the produce, meat and deli departments. But the overriding concern at this time is "convenience." Here is a typical comment from a St. Louis shopper:

"When we first moved to this area, we started comparison shopping and going to different places. But when the price of gas went up so high, it seemed like false economy to drive around too many place."