How to Choose a Mac

As I've mentioned in previous posts about laptop battery life, my 15" MacBook Pro (MBP) is over 3 years old. I'm now starting to seriously look at buying my next computer. How do you choose which to buy?! A few things conspire to make this a stressful decision for me:

1) I'm very particular about buying things like computers.

2) I rely on my portable computer as my only machine (by choice/design) and use it day and night for both astronomy and my side projects (like my blog!).

3) I have been traveling a good amount, around 3 or 4 conferences and a few weddings per year. This is going to continue (or maybe increase).

All of my past Apple machines have been excellent, and I've selected them each with care and forethought. Usually I wait to buy until the machine that makes sense gets an upgrade, and there is a whole niche industry in predicting/discussing such timescales. For example, I purchased this MBP shortly after an update, and right before I was starting my PhD program. I knew the best value for a high performance portable computer would be the 15" MBP model.

This time I'm very torn. I had been hoping that Apple would release a 15" MacBook Air, essentially unifying their laptop line. Largely this is what they've done, with the new slimed down and beefed up MacBook Pro Retina (MBPr).

The MBA has also grown, for its part. What used to be a big netbook has now blossomed into a respectable workhorse. For things like writing, traveling, and sheer beautify, the MBA is unmatched in my eyes. With a few affordable upgrades, the 13" MBA is on my radar as a real contender.

Both the Retina and the Air are capable of handling my day-to-day workload, both have been recently updated, both argue for portability. How to choose? MacBook Pro Retina or MacBook Air? Go for the top-of-the-line expensive heavier animal, or the urban and sophisticated marvel? I've asked people for their opinions, but the feedback was limited.

I decided to see if looking at numbers could help the matter! Is there an objectively better choice? Is one Apple laptop truly more desirable?
Resolution and RAM to Weight ratios as a function
of price for various Apple portable computers.
Here I've shown the screen resolution to weight ratio, and RAM to weight ratio, both as a function of price. These seemed to me the most important characteristics of a new laptop. As expected, the MBPr completely overpowers the resolution argument, while the MBA with upgraded RAM and CPU dominates the memory to weight ratio (with the MBPr in a respectable 2nd place).

These were interesting, as were other comparisons of the stats, but a clear winner didn't emerge. I needed a way to combine all of these characteristics, resulting in an "Awesomeness Parameter" that I could use. Then, simply pick the machine with the highest Awesomeness: easy!

I toiled for hours minutes, weighting the 4 parameters in various ways, and finally arrived at this:

The "Awesomeness Parameter", which includes Price, Weight,
Pixel Count, and RAM, shown as a function of the price.

The parameter "Q2" includes of all these factors: price, weight, resolution, and RAM. Each quantity is combined using my proprietary algorithm. The parameter is normalized to my current MBP (red), and thus Q2 = 1. The red dashed line shows how Qchanges if you simply decreased the price of my current machine.

While this statistic is meant in utter jocularity, it (strangely) accurately describes my feelings about the current laptop line. I've been very impressed with the 11" MBA, for instance, though it lacks the CPU power and HD space I need. Naturally the future Q3 parameter will include these stats as well.

The two top contenders are VERY close, with the MBPr scoring a 6.5 and the upgraded MBA a 6.7. By this metric, I should clearly purchase the upgraded 13" MBA...

Of course, I'm not guaranteeing my proprietary algorithm completely solves the problem. Still, it presents a curious idea: can I accurately quantify/model my desire for a computer, wrapping the decision up in to a single number?

What do you think? Which computer is better? Can we believe in a quantity like Q2? Chime in!


  1. what upgrades do you include for the upgraded MBA?

  2. That was with the bumped up RAM and processor ($100 each), but not the harddrive ($500). I also did not include the student discounts.

  3. As a MBP-13" user who started out with a 250GB hard drive, I think large HDD capacity is an important factor, especially if you're like me and you backup/archive all your iPhone photos/videos with your laptop. For a while I was spending a couple hours per month clearing my HDD and making tough choices about what to keep and what to toss. I got a 1TB drive last month and haven't looked back.

    Of course, a massive drive in a MBA $300 more, but if you're comparing it to a 15" MBPr it's not a huge leap. :)


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