According to Forbes own description of the methodology used, the answer is NO to the question posed.

"To calculate these figures, we... compiled an average of the five least-expensive plans in a particular county... We then used these county-based numbers to come up with population-weighted averages"

The question, which was based on Forbes' own claim, refers to "an average of 49% nationwide". Since no sample was taken of changes in any but the 5 lowest cost plans, it is mathematically impossible to extrapolate a "nationwide average" of anything but the cheapest plans. What portion of insurees this represents is unknown. We also don't know how many NEW insurees the post-ACA group includes, which could include those previously forced to buy more expensive policies due to preexisting conditions.

Even within the cheap-policy subgroup the comparison is too incomplete to be meaningful. For example, the study does not document the corresponding differences in the 5 plans pre- and post-ACA. This gives the impression consumers were getting less value for their money, but that may not be true when all factors are considered. For example, there are also changes in risk sharing between young and old, male and female, etc. So if you are a young man and see an increase in your insurance costs, it is useful to understand that part of that is to subsidize your mother's, wife's and daughters' insurance (women), as well as your own rates in the future (elderly). Unless you plan to stay single and die young, this should be part of your value calculations.

According to Forbes own description of the methodology used, the answer is NO to the question posed.

To calculate these figures, we used the same methodology we’ve used in the past. We compiled an average of the five least-expensive plans in a particular county pre-Obamacare, adjusted to take into account those with pre-existing conditions and other health problems. We then did the same calculation with the five least-expensive plans in each county under the Obamacare exchanges. We then used these county-based numbers to come up with population-weighted averages pre- and post-Obamacare.

The question, which was based on Forbes' own claim, refers to "an average of 49% nationwide". Since no sample was taken of changes in any but the 5 lowest cost plans, it is mathematically impossible to extrapolate a "nationwide average" of anything but the cheapest plans. What portion of insurees this represents is unknown. We also don't know how many NEW insurees the post-ACA group includes, which could include those previously forced to buy more expensive policies due to preexisting conditions.

Even within the cheap-policy subgroup the comparison is too incomplete to be meaningful. For example, the study does not document the corresponding differences in the 5 plans pre- and post-ACA. This gives the impression consumers were getting less value for their money, but that may not be true when all factors are considered. For example, there are also changes in risk sharing between young and old, male and female, etc. So if you are a young man and see an increase in your insurance costs, it is useful to understand that part of that is to subsidize your mother's, wife's and daughters' insurance (women), as well as your own rates in the future (elderly). Unless you plan to stay single and die young, this should be part of your value calculations.