Open Data and Personal Privacy

This is the second in a series of articles regarding a side project of mine, Read the first article here. Read part three here.

Once GlassboroMap and NJ Parcels started to get considerable traffic, I began receiving emails asking for the owner information to be removed from the site. While this was public data and, I imagine, has always been available, the easy ability for a search by name to bring up this information caused some individuals concern. Having known about assessment and parcel data for a while, I was initially surprised at the level of concern some individuals had about the site.

Of the emails received, most were courteous.


Others were angry.


Others informed me that publishing public data was actually a violation of human rights.


(This one was ironically humorous to me – the person had a somewhat unique name; a quick Google search produced this individual’s YouTube profile, where there were videos taken in front of and inside their home.)

As 2014 began and it looked like the increase in traffic was not a fluke and it continued to increase, I realized I needed to handle this better. I implemented a redaction table and started manually adding the property’s PIN when I’d receive an email. But this was manual and error prone. Sometimes an email would land in my spam folder and I wouldn’t see it. Other times, the email included a large amount of vitriol, but no indication of the property or the owner. So I developed a form so that the requests to redact the information could be a streamlined process.

To date, I have not declined any request (submitted using the form) to redact information from the site. Over 3,200 pages have had their owner name redacted from the page and over 5,100 redaction requests have been made. The difference in the number of requests and actual redactions is due to duplicate requests being made or the request includes a link to Google or some other website that is not NJ Parcels. Most importantly, the number of angry emails have dwindled down to virtually zero. I can only recall receiving three emails regarding information removal in all of 2015.

While redactions have been made within nearly every municipality, some have more requests than others.


Each point represents a municipality. The size of the points denote the overall count of redaction requests honored and the color value reflects redactions as a percentage of the total number of property records within the municipality.

Overwhelmingly, 98% the properties requested for redaction are residential containing 1 to 4 units. There are some oddities, 28 (.8%) redactions are for a vacant lot and 13 (.4%)  are for public property. The “public” property classes are also used for PILOTs and tax abatements; it’s not local governments or non-profits wanting to hide ownership information. I was surprised to see that several of the vacant lots are actually the communal land for a condominium organization. I’m not exactly sure why someone would want to suppress that information; if you have a guess why, please leave a comment or tell me on Twitter.

I’m likely going to revisit this data, comparing the redacted properties to those nearby. Are the redacted outliers in terms of assessed value, most recent sales price or overall square footage? I also collect the reason for redaction as a free-form text field that might have some interesting findings once thoroughly explored. I also encourage you to reach out to me if you have suggestions on other research might be interesting using this data.

Overall, I hope the approach I’ve taken with respect to personal privacy works. The information is public and I don’t feel as if I would be in the wrong if I did not institute some form of redaction. The presentation of the data in this manner was never meant to negatively impact anyone, nor violate anyone’s human rights, but in fact make it easier for interested homeowners and residents to better understand the real estate market around them.

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