While I can see that the latter could play a significant role if it were factored into somebody's assets, because that information hadn't been collected in 1984 (the first year used in the study for comparison purposes), it had to be omitted from the other two years for the sake of balance.
From personal experience the only way I could see private pension plans changing the results would be to further increase the gap between the lowest and the highest brackets. Usually the higher your income the greater the chance of having a high-return private pension plan.
The first thing the report tells us (all figures have been adjusted for inflation) is that from 1984 to 2005 the median wealth of Canadians rose by 26%. Now that sounds promising until you read the "but", which says that for the top 20% of families the median rose from $336,000 in 1984 to $551,000 in 2005, but for the bottom 20% the median, which had been zero in 1984, had fallen to (-$1,000) by 2005.
Unfortunately these figures are borne out by the even more depressing details of how the distribution of wealth has changed in the same time period. In 1984 the top 10% of families owned 52% of the wealth in Canada, while the lower 50% controlled only 5%. (This table provides a complete breakdown of the distribution of wealth over the periods in question.) By 2005 the upper 10% had increased their share to 58% while the lower 90% either remained the same or dropped.
So although the average wealth had increased over the course of time, it was simply a matter of the rich getting richer. Unfortunately it was also a matter of more people becoming poorer. The percentage of people with zero or negative wealth increased from 18% in 1984 having zero wealth to 24% in 2005 and 11% being in the negative to 14% in the same period.
The report also breaks down the results even further by age and gender. These statistics substantiate quite a few commonly held beliefs: young people aged 24 to 35 saw their median wealth drop by 50% in the period covered by the study. Those in the next age bracket, 35 to 54, who had a university degree saw their income rise by 39%. (By thirty-five most former university graduates would have paid off their student loans, which until that time would have obviously affected their total wealth.)
Those without a degree were in the same boat as the people in the lower age bracket. If that isn't proof of the difference a degree can have on your earning power and your ability to generate sufficient income to accumulate real assets, I don't know what is. It's also a pretty strong argument in favour of ensuring universal access to higher education through grants and loans.