An avalanche of innovation?
23rd September 2010
It seems that, almost despite the uncertain times or maybe because of them, it feels like an era of change on the technology front. Computing is the domain of many of the postings on this website, and a hell of a lot seems to be going mobile at the moment. For a good while, I managed to stay clear of the attractions of smartphones until a change of job convinced me that having a BlackBerry was a good idea. Though the small size of the thing really places limitations on the sort of web surfing experience that you can have with it, you can keep an eye on the weather, news, traffic, bus and train times so long as the website in question is built for mobile browsing. Otherwise, it's more of a nuisance than a patchy phone network (in the U.K., T-Mobile could do better on this score, as I have discovered for myself; thankfully, a merger with the Orange network is coming next month).
Speaking of mobile websites, it almost feels as if a free for all has recurred for web designers. Just when the desktop or laptop computing situation had more or less stabilised, along came a whole pile of mobile phone platforms to make things interesting again. Familiar names like Opera, Safari, Firefox and even Internet Explorer are to be found popping up on handheld devices these days along with less familiar ones like Web 'n' Walk or BOLT. The operating system choices vary too, with iOS, Android, Symbian, Windows and others all competing for attention. It is the sort of flowering of innovation that makes one wonder if a time will come when things begin to consolidate, but it doesn't look like that at the moment.
The transformation of mobile phones into handheld computers isn't the only big change in computing, with the traditional formats of desktop and laptop PC's being flexed in all sorts of ways. First, there's the appearance of netbooks, and I have succumbed to the idea of owning an Asus Eee. Though you realise that these are not full-size laptops, it still didn't hit me how small these were until I owned one. They are undeniably portable, while tablets look even more interesting in the aftermath of Apple's iPad. Though you may call them over-sized mobile photo frames, the idea of making a touchscreen do the work for you has made the concept fly for many. Even so, I cannot say that I'm overly tempted, though I have said that before about other things.
Another area of interest for me is photography, and it is around this time of year that all sorts of innovations are revealed to the public. It's a long way from what, we thought, was the digital photography revolution when digital imaging sensors started to take the place of camera film in otherwise conventional compact and SLR cameras, making the former far more versatile than they used to be. Now, we have SLD cameras from Olympus, Panasonic, Samsung and Sony that eschew the reflex mirror and prism arrangement of an SLR using digital sensor and electronic viewfinders while offering the possibility of lens interchangeability and better quality than might be expected from such small cameras. Lately, Sony has offered SLR-style cameras with translucent mirror technology instead of the conventional mirror that is flipped out of the way when a photographic image is captured. Change doesn't end there, with movie making capabilities being part of the tool set of many a newly launched compact, SLD and SLR camera. The pixel race also seems to have ended though increases still happen as with the Pentax K-5 and Canon EOS 60D (both otherwise conventional offerings that have caught my eye, though so much comes on the market at this time of year that waiting is better for the bank balance).
The mention of digital photography brings to mind the subject of digital image processing and Adobe Photoshop Elements 9 is just announced after Photoshop CS5 appeared earlier this year. It almost feels as if a new version of Photoshop or its consumer cousin is released every year, causing me to skip releases when I don't see the point. Elements 6 and 8 were such versions for me, so I'll be in no hurry to upgrade to 9 yet either, even if the prospect of using content aware filling to eradicate unwanted objects from images is tempting. Nevertheless, that shouldn't stop anyone trying to exclude them in the first place. In fact, I may need to reduce the overall number of images that I collect in favour of coming away with only the better ones. The outstanding question on this is: can I slow down and calm my eagerness to bring at least one good image away from an outing by capturing anything that seems promising at the time? Some experimentation but being a little more choosy can save work later on.
While back on the subject of software, I'll voyage in to the world of the web before bringing these meanderings to a close. It almost feels as if there are web-based applications following web-based applications these days, when Twitter and Facebook nearly have become household names and cloud computing is a phrase that turns up all over the place. In fact, the former seems to have encouraged a whole swathe of applications all of itself. Applications written using technologies well-used on the web must stuff many a mobile phone app store too and that brings me full circle for it is these that put so much functionality on our handsets with Java seemingly powering those I use on my BlackBerry. Then there's the spat between Apple and Adobe regarding the former's support for Flash.
To close this mental amble, there may be technologies that didn't come to mind while I was pondering this piece, but they doubtless enliven the technological landscape too. However, what I have described is enough to take me back more than ten years ago, when desktop computing and the world of the web were a lot more nascent than is the case today. Then, the changes that were ongoing felt a little exciting now that I look back on them, and it does feel as if the same sort of thing is recurring though with things like phones creating the interest in place of new developments in desktop computing such as a new version of Window (though 7 was anticipated after Vista). Web designers may complain about a lack of standardisation, and they're not wrong, yet this may be an era of technological change that in time may be remembered with its own fondness too.
Exploring the option of mobile broadband
20th September 2010
Last week, I decided to buy and experiment with a Vodafone PAYG mobile broadband dongle (the actual device is a ZTE K3570-Z) partly as a backup for my usual broadband (it has had its moments recently) and partly to allow me to stay more connected while on the move. Thoughts of blogging and checking up on email or the real-time web while travelling to and from different places must have swayed me.
Hearing that the use of Windows or OS X with the device had me attempting to hook up the device to Windows 7 running within a VirtualBox virtual machine on my main home computer. When that proved too big a request from the software setup, I went googling out of curiosity and found that there was a way to get the thing going with Linux. While I am not so sure that it works with Ubuntu without any further adjustments, my downloading of a copy of the Sakis3G script was enough to do the needful, and I was online from my main OS after all. So much for what is said on the box...
More success was had with Windows 7 as loaded on my Toshiba Equium notebook, with setting up and connections being as near to being effortless as these things can be. Ubuntu is available on there too, courtesy of Wubi, and the Sakis3G trick didn't fail for that either.
That's not to say that mobile broadband doesn't have its limitations, as I found. For instance, Subversion protocols and Wubi installations aren't supported, but that may be a result of non-support of IPv6 than anything else. Nevertheless, connection speeds are good as far as I can see, though I yet have to test out the persistence of Vodafone's network while constantly on the move. Having seen how flaky T-Mobile's network can be in the U.K. as I travel around using my BlackBerry, that is something that needs doing, yet all seems painless enough so far. However, the fact that Vodafone uses the more usual mobile phone frequency may be a help.
Creating a Data Set Containing Confidence Intervals Using PROC UNIVARIATE
5th September 2010
While you could generate data sets containing means and confidence intervals using PROC SUMMARY or PROC MEANS, curiosity and the need to verify a program using a different technique were what drove me to consider using PROC UNIVARIATE for the task. For the record, the PROC SUMMARY code is below and the only difference between it and MEANS is that it doesn't produce output by default, something that's not needed in this case anyway. Quite why there are two SAS procedures doing the same thing is beyond me, though I do wonder if the NOPRINT option was a later addition than these two procedures. The LCLM and UCLM keywords are what triggers the calculation of confidence limits and the ALPHA option controls the confidence interval used; 0.05 specifies a 95% interval, 0.1 a 90% one and so on.
proc summary data=sashelp.class mean lclm uclm alpha=0.05;
var age;
output out=sasuser.lims mean=mean lclm=lclm uclm=uclm;
run;Given that I have had PROC UNIVARIATE producing statistics that MEANS/SUMMARY didn't in previous versions of SAS (I believe that it was standard deviation that was absent from MEANS/SUMMARY), I might have expected the calculation and export of confidence limits to a data set to be straightforward. Sadly, it's not a case of simply adding LCLM and UCLM keywords in the OUTPUT statement for the procedure, and ODS OUTPUT is needed to create the data set instead. An ODS SELECT statement is needed to pick out the BasicIntervals output object (UNIVARIATE creates quite a few, it seems) that is created through specification of the CIBASIC and ALPHA (performs the same role as it does for PROC MEANS/SUMMARY) options on the PROC UNIVARIATE statement. The reason for the ODS LISTING and ODS RTF statements below is to stop output being sent to the output window in a standard SAS session. For some reason, it appears that you need the sending of output to one of the LISTING, HTML or RTF destinations or there will be no data in the data set; I met up with the same behaviour when using ODS PS, an ODS PRINTER destination. The data set will contain statistics for mean, standard deviation and variance, so that's why there is a WHERE clause on the ODS OUTPUT statement.
ods listing close;
ods rtf body="c:\temp\uni_eg.doc";
ods select BasicIntervals;
ods output BasicIntervals=sasuser.stats(where=(lowcase(parameter)="mean") );
proc univariate cibasic alpha=0.05 data=sashelp.class;
var age;
run;ods output close;
ods rtf close;
ods listing;
Using ODS Graphics to Create Plots Using PROC LIFETEST
3rd September 2010
One of the nice things about SAS 9.2 is that creation of statistical graphics is enhanced using the Output Delivery System (ODS). One of the beneficiaries of this is PROC LIFETEST, a procedure that gained a lot when data sets could be created from it using ODS OUTPUT statements. Before that, it was a matter of creating text output and converting it to a SAS data set using Data Step, and that was a nuisance on a system that attached special significance to output destinations set up using PROC PRINTTO. What you’ll find below is a sample of the type of code for creating a Kaplan-Meier survival plot for time to adverse events resulting in discontinuation of study treatment, with actual and censored times. The IMAGENAME parameter on the ODS GRAPHICS statement line controls the name of the file, and it is possible to change the type using the IMAGEFMT parameter too.
ods graphics on / imagename=”fig5″;
proc lifetest data=km3 method=km plots=survival;
time timetoae*cens_ae(0);
run;
ods graphics off;On Making PROC REPORT Work Harder
1st September 2010
In the early years of my SAS programming career, there seemed to be just the one procedure to use if you wanted to create a summary table. That was TABULATE and it was great for generating columns according to the value of a variable such as the treatment received by a subject in a clinical study. To a point, it could generate statistics for you too, and I often used it to sum frequency and percentage variables. Since then, it seems to have been enhanced a little and surprised me with the statistics it could produce when I had a recent play. Here's the code:
proc tabulate data=sashelp.class;
class sex;
var age;
table age*(n median*f=8. mean*f=8.1 std*f=8.1 min*f=8. max*f=8. lclm*f=8.1 uclm*f=8.1),sex
/ misstext="0";
run;When you compare that with the idea of creating one variable per column and then defining them in PROC REPORT as many do, it looks more elegant and the results aren't bad either, though they can be tweaked further from the quick example that I generated. That last comment brings me to the point that PROC REPORT seems to have taken over from TABULATE wherever I care to look these days, and I do ask myself if it is the right tool for that for which it is being used or if it is being used in the best way.
While using Data Step to create one variable per column in a PROC REPORT output doesn't strike me as the best way to write reusable code, there are ways to make PROC REPORT do more for you. For example, by defining GROUP, ACROSS and ANALYSIS columns in an output, you can persuade the procedure to do the summarising for you and there's some example code below with the comma nesting height under sex in the resulting table. Sums are created by default if you do this, and forgoing an analysis column definition means that you get a frequency table, not at all a useless thing in numerous instances.
proc report data=sashelp.class nowd missing;
columns age sex,height;
define age / group "Age";
define sex / across "Sex";
define height / analysis mean f=missing. "Mean Height";
run;For those times when you need to create more heavily formatted statistics (summarising range as min-max rather showing min and max separately, for example), you might feel that the GROUP/ACROSS set-up's non-display of character values puts a stop to using that approach. However, I found that making every value combination unique and attaching a cell ID helps to work around the problem. Then, you can create a format control data set from the data like in the code below and create a format from that which you can apply to the cell ID's to display things as you need them. This method does make things more portable from situation to situation than adding or removing columns depending on the values of a classification variable.
proc sql noprint;
create table cntlin as
select distinct "fmtname" as fmtname, cellid as start, cellid as end, decode as label
from report;
quit;proc format lib=work cntlin=cnlin;
run;