[andych]

Should one be more aggresive?? You won much making a game. Losing 50/100 is not that matter.

Analysis please

[Gerben42]

Well basically you are playing total points:

Let's assume the question is to bid 4♠ or not.
Not vulnerable if you bid it and make it: +420
If you bid it and don't make it: -50
If you don't bid it and make it: +170
If you don't bid it and don't make it: +140

So you either win 250 points or lose190, which means you need 43% chance to make it to break even.

Vulnerable you either win 450 points or lose 240, which means you need 35% chance to make it to break even.

Now small slam:
NV you either win 500 (980 to 480) points or lose 500 (450 to -50), so 50% is needed.
V you either win 750 (1430 to 680) or lose 750 (650 to -100), so again 50% is needed.

Finally GRAND slam:
NV you either win 500 (1510 to 1010) or lose 1030 (980 to -50), you need 67% chance.
V you either win 750 (2210 to 1460) or lose 1530 (1430 to -100), so again 67% chance.

Just FYI

[MickyB]

That assumes that you were making your part-score, and that you won't get doubled in game.

[Gerben42]

Right but this is the basic strategy.