The rates themselves are, by law, the lowest rate that the stations charge (to avoid stations charging different rates based on whether they support that candidate) - so that's not really that informative. It's actually knowing that Candidate X purchased 800 points of TV time in Market A and 1200 points in Market B that is interesting. Currently, this information is available, but only by driving to the stations during business hours to view them, which is of course not very useful.
You'd need more than 50% to not return the form before it would make any practical difference at the statistical level.
Except that the census isn't designed solely for macro-level statistical information. One of the most important roles of a census is determining a city/county/state's population, which is used to allocate funding, and determine the number of representatives in the US House and state houses/senates, which does have a significant impact on the makeup of those bodies.
Return rates are not uniform across the board. Large cities are notoriously under-counted, because of the difficulty of counting the homeless population, renters, those who move during the course of the census, those who do not speak English (even though the Census prints in multiple languages, return rates are still lower among non-English speakers), and various other groups that tend to be much more prevalent in large cities than in smaller cities and more middle-class suburban neighborhoods. This map of Census forms returned county-by-county provides an interesting look at the issue. While the percentages can't be considered completely accurate due to issues like vacant apartments, etc, there's still significant variance. In New York state, for example, mail return rates per county range from 43% to 84%. That's a staggering variance, and when it comes to ensuring that residents have adequate funding and representation, having fairly accurate results is essential.
As an aside, statistical sampling for the census has been discussed in the past to avoid these issues. I'm not opposed to using a reasonable sampling technique, so long as it accounts for areas with statistically low return rates. However, Republicans oppose sampling because they feel it overcounts groups that tend to vote Democratic (and, Democrats tend to support sampling because they feel it's a more accurate count). In 1999, the Supreme Court ruled that sampling cannot be used to determine population for the purposes of apportioning US congressional seats, and while it could be used for drawing state/local lines and for allocating federal funds, it's such a political football that it probably won't happen in the foreseeable future.
"Over the weekend, we learned about a new scenario that identifies ways that Firefox could also be used as the entry point," said Window Snyder of Mozilla. "While browsing with Firefox, a specially crafted URL could potentially be used to send bad data to another application.
"We thought this was just a problem with IE," Snyder continued. "It turns out, it is a problem with Firefox as well.""
Link to Original Source
"[The 29,000] includes just the predators who signed up using their real names and not the ones who failed to register or used fake names," Cooper said in the statement. Cooper is one of eight state attorneys general who asked MySpace in May to turn over the names of users who are registered sex offenders.
In May, MySpace reluctantly revealed it had uncovered 7000 sex offenders."