Linked List: April 30, 2015

Thursday, 30 April 2015

Phone Sales in China 

While on the subject of charting sales trends, here’s an interesting one from Ben Bajarin on smartphone sales share in China. A lot of movement just in the last year alone.

Kieran Healy, following up on Dr. Drang’s post on the iPad’s sales slump:

Dr Drang put up a characteristically sharp post looking at sales trends in Apple Macs, iPhones, and iPads. He used moving averages to show long-term sales trends effectively, and he made a convincing argument that iPad sales are in decline. I ended up grabbing the sales data myself from barefigur.es and more or less copying him. Instead of a moving average, here’s a plot of the trends showing the individual sales figures with a LOESS smoother fitted to them.

Truly fascinating visualizations of Apple’s sales trends for iPhone, iPad, and Mac.

Moving Averages and the iPad 

Loved this post from Dr. Drang, on how to accurately visualize the declining trend in iPad sales:

There are myriad other ways to smooth a graph without switching to cumulative figures. One of the simplest is the moving average. In this technique, instead of plotting the raw data, you plot the average of a few data points in the neighborhood of each time value.

For many data sets, the best size of this neighborhood is not obvious. With Apple’s sales figures, though, I think it’s clear that the best choice is to average over four quarters: the quarter that you’re plotting and the three previous. This smooths over the seasonal jumpiness while not including so much past data as to ignore real trends.

As for why iPad sales have hit this slump, I really liked this explanation from one of Drang’s readers:

Ben Packard, in an email, suggests my reason for dismissing the durability explanation for the iPad sales decline is weak. The Mac, he says, has been around long enough for there to be substantial numbers of owners at every stage of ownership, but far more iPad users are still on their first iPad. Whatever the long term replacement cycle of iPads turns out to be, we’re still in the first one, too early for variations in when people bought their most recent iPad to have evened out.

Wrist Tattoos Interfere With Apple Watch Sensors 

Serenity Caldwell, writing for iMore:

Recently, we’ve been hearing reports from Twitter and Reddit that the Apple Watch’s plethysmograph sensor plays not-so-nicely with wrist or arm sleeve tattoos. The ink pigmentation interferes with the sensor’s ability to read your heart rate — and with it, the Watch’s ability to assess whether or not it’s maintaining skin contact. […]

For those wondering: natural skin pigmentation doesn’t block light the same way artificial ink pigment or even scar tissue does, so you shouldn’t run into a problem if your skin is naturally darker.