Facebook is the most famous company that makes money by compiling data dossiers about people, but it is far from the oldest. That accolade probably belongs to Acxiom, founded in 1969, which is reported to have files on 500 million people worldwide, including 190 million in the U.S.

Today Acxiom stepped out of the shadows a little, launching a website called About the Data where people can view some of what the company knows about them. Doing so requires entering your name, address, date of birth and part of your social security number (Acxiom’s transparency is apparently aimed only at the U.S. residents in its database).

The data the site showed me when I did that was minimal. Acxiom knows my gender, but has my marital status wrong. Most fields were filled with “There is no data available about you for this category.” The most personal thing Acxiom told me was that it knows what type of credit card I own and use.

Other people report seeing much richer reports, along with many inaccuracies:

According to Acxiom, I am 64-65, have 1 child, vote Republican. NAILED IT. (41, 3 kids, Dem. SO CLOSE.) http://t.co/6cywBndVNj.

— Rick Klau (@rklau) September 4, 2013

Acxiom seems to often get people’s ethnicity wrong, something it guesses at based on a person’s last name. In a report last week, in advance of Acxiom laucnhgin its new site, the New York Times notes that the company’s CEO Scott Howe is himself a victim of that error, being labeled as having Italian rather than Norwegian heritage. The Times doesn’t say why Axciom still uses an apparently unreliable method.

You won’t find all the data Acxiom has about you on About the Data. The company is known to maintain much more detailed records than the site shows, including information such as a person’s height and weight. The only way to get a full version of your Acxiom file is to mail them a $5 check. Even that may not capture the most important things about Acxiom’s data on you. The company sorts people into socioeconomic buckets with names including “Latchkey leasers” and “McMansions and Minivans”. It is interpretations like those that really determine how data held by the broker affects a person, whether by tuning the online ads they see, or the deals companies using Acxiom data offer to them.

The most curious feature of Acxiom’s new site is that a person can edit their own data, a feature described as helping the company improve its accuracy. Howe told the Times he believes that feature could lead to Acxiom becoming a consumer brand people volunteer data to in order to tune the ads they see online. That suggests to me that despite Howe’s company slurping up a lot of data on consumers, he apparently has little idea of what people are really like.