My selection for the week is determined by the way the betting line conforms to my personal opinion.

As a rule, my Sunday night figures will be very close to those posted in Las Vegas the following day. Rarely is the variance more than a point. Every once in a while, however, a disparity occurs that forces attention on a game I had planned to pass. This week provided one such example.

I made Philadelphia a five-point favorite against Minnesota. Bob Martin, the head linesman for the nation's football bettors, opened the game at 3 1/2. The 1 1/2-point difference will prompt me to risk an imaginary $250 on the Eagles, who are 6-0 in the National Football League, 6-0 against the spread and a sounder squad than the Vikings.

This does not mean I would automatically pick a game involving two weak teams just because the spread was sharply different from what I had thought it would be. I tend to ignore the bad clubs. They don't know how they're going to perform from week to week, so how can I? Although the weak have become stronger and the strong weaker in recent seasons, they still represent too high a risk, although I happily will go against them with a good team in the right situation.

Minnesota, in the hands of many coaches, would be a weak team. The personnel is not outstanding. But Bud Grant is special. For years, when he had the Purple People Eaters, he was the league's arch conservative. When the 1978 rules changes radically affected the game, Grant changed. He has a team that is wonderfully pass-oriented and takes advantage of the league's mad desire for 100-point games.

Not many coaches, and certainly not many old-guard coaches, made the transition so quickly or successfully.

Still, I have to think Philadelphia has too much balance for the Vikings to handle. Giving only 3 1/2 is also a factor, although admittedly a small one. Tommy Kramer has become the league's second most dangerous passer, surpassed only by San Diego's Dan Fouts, whom he beat last week.

Other selections this week are Cincinnati, getting two points at home against Pittsburgh; San Francisco, in a game rated even, in Milwaukee against Green Bay; San Diego, giving 4 1/2 at Baltimore, and Dallas, giving four at home Sunday night to Los Angeles. The risk is $250 on each except Dallas, which draws $500.

I was not impressed by the Steelers' performance last week in beating Cleveland. The Pittsburgh defense is improving, but has a long way to go, and the Bengals should be ready for this one. When was the last time Cincinnati was playing for the division lead seven weeks into the season?

San Diego is having problems on defense again, but its difficulties are not as serious as Baltimore's. If Fouts doesn't put 40 points on the board, it won't be because of lack of cooperation from the Colt secondary.

San Francisco is coming on. I mentioned that two weeks ago in picking the 49ers over New Orleans, but was not impressed by their performance against the Saints. So I went against the 49ers the next two weeks, and it proved costly. I haven't been right all year about Green Bay, either. Proceed at your own risk.

This week's major pick is Dallas. The Cowboys quit on Tom Landry Sunday in San Francisco. I can't imagine that will happen again soon, if ever. The L.A. quarterback situation is unsettled because of Pat Haden's injury. This should be a logical game in which the Cowboys can recover their pride.

In other games, Las Vegas lists Buffalo 3 1/2 over the New York Jets, Denver at Kansas City even, New England 3 1/2 over Houston, Cleveland 10 1/2 over New Orleans, Seattle 1 1/2 over the New York Giants, Atlanta eight over St. Louis, Oakland four over Tampa Bay, Miami seven over Washington and, Monday night, Detroit 6 1/2 over Chicago.

Last Week$125

Season Totals -- $125-- $425

Last week's results: Green Bay giving 3 1/2, lost to Tampa Bay, 21-7, minus $275; Los Angeles, getting four, defeated Atlanta, 37-35, plus $250; Kansas City even, defeated Oakland, 27-0, plus $250; Denver giving seven, defeated Detroit, 27-21, minus $550; Dallas, giving 4 1/2, lost to San Francisco, 45-14, minus $550; Buffalo giving four, defeated Miami, 31-21, plus $750.

Won-lost record, 14-12.