Unpacking .pkg files in OS X with BetterZip

I had cause today to try to unpack a .pkg file. I had installed PDF File Unlocker and found it was a bit pants1. Unfortunately, it installed from a .pkg file and there was no uninstaller or list of files that get installed, so I wanted to make sure I’d efficiently purged it from my system.

I have BetterZip, which is a really good utility for unzipping basically any file on the planet for OS X. I will just note at this stage that I have an older version of the utility and I haven’t upgraded to BetterZip 2, but I’ve got a lot of use out of the app. The below steps rely on having BetterZip. If you’d like to do it without BetterZip, I found this blog post and this Stack Overflow post to be very helpful in informing my actions.

  1. Change the extension from .pkg to .xar.
  2. Open the file with BetterZip. This took a while on my system but did eventually work.
  3. Three files should appear: Payload, Bom, and PackageInfo.
  4. PackageInfo: Just open this in your favourite text editor.
  5. Payload:
    • Add the extension .cpio.gz.
    • Open the file with BetterZip.
  6. Bom:
    • Open Terminal.
    • Navigate to the file.
    • lsbom Bom

Hopefully that all helps somebody else, too!


  1. If you generate a PDF with the free trial, it’ll be the first half of the PDF and every time you open it Adobe Acrobat will give you a little pop-up window. I disliked it. 

Facebook and their psychology experiment

Today it was reported by the AV Club that Facebook (or their researchers) has recently submitted a paper to a journal of psychology exploring the impact of social media on mood. It’s actually quite an interesting finding, if perhaps an expected result: people get happier or sadder depending on whether the mood of their news feed is light or heavy.

But the ethics are a bit problematic. Facebook conducted this experiment by skewing users’ feeds to either be more positive or more negative and then seeing whether future posts from a user were likely to be more negative or positive as a result. This means that they manipulated users’ emotions, which is somewhat concerning. It’s entirely legal under the terms of the agreements you make with Facebook when you open an account, but is it ethical? After a conversation with my girlfriend, I rather think not: informed consent is the key thing here, and the users in this experiment did not give informed consent despite any agreements they might have clicked ‘OK’ on.

What really interests me, however, is the question of utility. There’s an argument that if Facebook can make its users more happy by manipulating their feed, then they should. But what this exposes is the question of whether Facebook is an information service or an entertainment service: is the primary goal to keep you updated about your friends and what they’re doing, or is the primary goal to entertain your users and make them happy? This research makes me think Facebook is more interested in the latter, compared to Twitter, which seems to focus more on the former1. That’s potentially an insight into Facebook’s goals and what they’re aiming to do in the future.

The thing I’m most curious about isn’t the utility but rather the way in which the experiment was conducted. I don’t get why Facebook used the methodology they did. They manipulated the feed to give more positive and more negative messages and measured the change in mood of the resulting status updates: that’ll get you the results you want, sure. But why not the following methodology?

  1. Choose a user.
  2. Let the existing algorithms automatically generate that user’s feed.
  3. Monitor those algorithms’ output over a month and determine the average happiness of their feed and their statuses.
  4. Keep monitoring, but now looking for a period of time which deviates from the average happiness by some amount.
  5. Upon measuring this, measure the change in happiness of status posts.

It would surely allow researchers to explore the same question but without actually needing to manipulate users’ emotions at all, thus neatly removing any ethical qualms whilst still allowing interesting research to be conducted. The level of happiness might be hard to quantify, but they’ve already quantified it in the study so I don’t see that as a huge stumbling block. Is there a flaw I’m not seeing here, and if so, what is it?

Edited on 29 June 2014: Thanks to the commenters for their intriguing discussion of this idea! A lot of people have pointed out that this is not the equivalent of an intervention study; this has been noted both in the comments on this piece and by @tedsvo and @masnick (who wrote a follow-up to my blog post talking about my idea) on Twitter.

I’m aware that this is the case, but my background is in solar-terrestrial physics and so none of my research can be based on intervention studies. As a result, the scientists in my field have to develop techniques to explore causality based on observed correlations. What I’m essentially proposing, above, is a superposed epoch analysis in which users’ happiness is expressed for a number of days on either side of observed impacts on newsfeed positivity. It isn’t as definitive as Facebook’s method, but it is a more ethical way to conduct research which would hopefully shed light on the questions at hand.

I would be fascinated to see whether the same result could be reached using a non-intervention-based method, and I wonder whether the advent of large datasets from companies like Facebook and Google could be an opportunity for physicists to utilise data analysis skills over large timescales?


  1. This might also be why businesses are starting to find their outreach on Twitter is much more effective than on Facebook: Facebook is focusing on users to the detriment of businesses posts appearing in feeds, whereas Twitter isn’t doing quite the same thing. (Both companies allow sponsored posts so the monetisation strategy is equal between the two.) 

Procrastinations #13

The cover of Procrastinations #13, showing a member of convention staff literally burned from the shoulders up.

Procrastinations #13 is finally here! Featuring contributions from myself, Claire Brialey, Meg Frank, Crystal Huff, and Hannah Peaden, I’m excited to be able to share it with you all. This issue’s theme was convention burnout, and you can download it now!

Nominating podcasts for the Hugo Awards

Recently, I read a tweet that moved me to respond to the author.

The reason Jason tweeted to say that his podcast (The Incomparable) wasn’t eligible in the Fancast category was that he takes sponsorship. Both he and I thought that rendered him ineligible for any fannish category, due to the fact it represents a revenue stream.

A photograph showing previous Hugo Awards on display at a convention

I tweeted at Jason, and we discussed podcasts and their place in the list of Hugo Award categories. There are two categories in the last couple of years that have seen podcasts nominated. The first and most obvious is Best Fancast, in which a range of fannish podcasts have been nominated but which is specifically for non-professional ventures. The other is Best Related Work, in which Writing Excuses was nominated in both 2012 and 2013.

In which category would The Incomparable belong? Upon reading the WSFS Constitution1 we find:

A Professional Publication is one which meets at least one of the following two criteria: (1) it provided at least a quarter the income of any one person or, (2) was owned or published by any entity which provided at least a quarter the income of any of its staff and/or owner.

The definition of the Best Fancast category as expressed in the same document is — to preçis — any podcast that is “non-professional”, i.e. any podcast that does not meet either of the above criteria. I have been told that the reason that Writing Excuses is not eligible as Best Fancast is because it is published by Brandon Sanderson’s company, which qualifies it as a professional work.

What this does mean, however, is that any podcast with sponsorship and adverts can be nominated for Best Fancast, as long as that sponsorship does not make enough money to qualify the podcast as professional.

Podcast collectives

Where this becomes somewhat less clear is in the case of podcast collectives. The Incomparable is a part of the 5by5 network, which employs Dan Benjamin on a full-time basis, so anything published by or owned by 5by5 counts as a professional work. A podcast collective does not own the podcasts that belong to it, but I don’t know how a Hugo Awards administrator would rule on whether a collective counts as publishing the podcasts that belong to it. Jason argued that it wouldn’t in an email to me, writing:

I own my show (5by5 hosts it and sells some of the advertising, but I have all creative control as well as our separate site at theincomparable.com) so 5by5′s business status probably doesn’t connect.

I agree with Jason — it seems clear to me that podcast collectives are not publishers. Despite my opinion, however, the word ‘publish’ is not explicitly defined in the WSFS Constitution and so I can’t be sure of how an administrator would rule on the issue. I would argue that the fact that 5by5 has no editorial control over the podcast means that they don’t publish it, but I suspect there are arguments one could put forward to argue the reverse. I hope that future administrators would agree with me, but without a test case there’s no way to know.

Therefore, the only logical conclusion is to nominate The Incomparable as Best Fancast and watch what the administrators do! Go nominate it now, and I’ll write a follow-up blog post when it’s announced as a nominee at Satellite 4.

Thanks to Andrew Trembley and Warren Buff for discussing this subject with me!


  1. I apologise for linking to such a completely awful website, but unfortunately it’s the best way to link readers to the constitution. Hopefully one day it’ll get a fresh coat of paint.