> If only 40% of students get placed -- that's still 40% more than would have been placed without Lambda, right?

You can't draw that conclusion without a control group. It is entirely possible that a control group that spent that boot camp time doing independent study and job hunting would have higher placement rates and that Lamda school would thus have a negative effect.

I would guess that Lamda school does have a positive effect but that effect is smaller than 40%.