Optimizely reliability - optimizely

We started using Optimizely and we're blown by the results so we started creating aggressive campaigns.
But then we realized something was wrong and I would appreciate any help we can get.
We tested (for example) on the homepage instead of a blue CTA, we created a variation with a green CTA and we saw a 35% increase in conversions with the variation. So then we switched things and set the green CTA as the control and the blue CTA as the variation. If it was really true that the green CTA is better we should now be seeing a 35% decrease in conversions with the variation of the blue CTA.
Instead, the variation came back with a higher conversion rate.
I can't pinpoint what we're doing wrong, but in general all the variations come in with a higher success rate than the control, but if we switch things around and set the variation as the control, the results don't switch.

How do you measure conversions? It's usually a good practice to measure in more ways than once - for example, for a CTA experiment I would measure clicks, landing on the page where the link redirects, valid form submissions etc. Expanding your view on the data and see how a change will affect other parts of the user experience is always a good idea.

Try:
On Results page apply different segments to identify improvement in each variation
I recommend setting a 90% of statistical significance
If you tested in 2 separate test, maybe you didnt let it the right time i usually prefer to have them by a week to avoid seasonality,

Are you making these adjustments to an experiment that has already been running? You should keep in mind that users are bucketed once you've started an experiment so making adjustments like switching who belongs to a control or not, after or whilst an experiment has run will not be starting you fresh so to say. If you're making the adjustments you describe then you'll need to create a new experiment.

Related

UI Labeling things for age at a glance

I have a web app for booking entertainers. I would like to see at a glance how long it's been since I booked them. Currently, I'm using colored labels.
performers booked in the future : green
performers booked recently :light blue
performers booked long ago : dark blue
performers booked never : black
Is there a typical way to label things that might be better than this? It's kinda weird. When I distribute this app, I want it to be immediately clear to the users that they are seeing a visual representation of how long ago the performer was booked.
I find there is a lot competing for the attention of the user, so maybe you can reduce the overall visual weight a bit.
Some things I'd look into:
sorting the list according to the booking date
grouping the list
reducing the amount of different booking states to 2 or 3
replace the tags by two different display styles: relevant to the user take up more space (future and recently booked) while the rest gets a collapsed view
Generally speaking it's better to improve a UI by leaving stuff out instead of adding more styles to fix a broken UI. What you choose depends on the priority of your use cases.
Not directly related to your question, the available button, the gray category tags and the bright booking tag are nearly unledgible due to a lack of contrast.
All the best with your app :)
While I agree with previous poster that there is overall a lot of competition, I wanted to give you an idea for your question about the dates and labels:
Overall, using colored labels, you’ll have four different colour blocks competing —> tag, Edit, Availability, and this new Booking Status one. So instead, you could consider using an icon with your text instead and thereby do away with the colour.
I use FontAwesome codes (https://fontawesome.com/cheatsheet?from=io) below for simplicity, but most icon sets should have a comparable one.
Future: [fa-calendar-plus] in 1 month
Recent: [fa-check-square] or [fa-clock] 2 days ago
Past: [fa-calendar-check] 02/2018
Performers Booked Never doesn’t need a label, since it’s the only exception and doesn't involve any form of booking.
On a side note:
- Perhaps consider reducing the number of hearts / blocks you have on each line, or using one heart with varying fills perhaps. I think it might be your primary culprit for the “clutter”.

performance of layered canvases vs manual drawImage()

I've written a small graphics engine for my game that has multiple canvases in a tree(these basically represent layers.) Whenever something in a layer changes, the engine marks the affected layers as "soiled" and in the render code the lowest affected layer is copied to its parent via drawImage(), which is then copied to its parent and so on up to the root layer(the onscreen canvas.) This can result in multiple drawImage() calls per frame but also prevents rerendering anything below the affected layer. However, in frames where nothing changes no rendering or drawImage() calls take place, and in frames where only foreground objects move, rendering and drawImage() calls are minimal.
I'd like to compare this to using multiple onscreen canvases as layers, as described in this article:
http://www.ibm.com/developerworks/library/wa-canvashtml5layering/
In the onscreen canvas approach, we handle rendering on a per-layer basis and let the browser handle displaying the layers on screen properly. From the research I've done and everything I've read, this seems to be generally accepted as likely more efficient than handling it manually with drawImage(). So my question is, can the browser determine what needs to be re-rendered more efficiently than I can, despite my insider knowledge of exactly what has changed each frame?
I already know the answer to this question is "Do it both ways and benchmark." But in order to get accurate data I need real-world application, and that is months away. By then if I have an acceptable approach I will have bigger fish to fry. So I'm hoping someone has been down this road and can provide some insight into this.
The browser cannot determine anything when it comes to the canvas element and the rendering as it is a passive element - everything in it is user rendered by the means of JavaScript. The only thing the browser does is to pipe what's on the canvas to the display (and more annoyingly clear it from time to time when its bitmap needs to be re-allocated).
There is unfortunately no golden rule/answer to what is the best optimization as this will vary from case to case - there are many techniques that could be mentioned but they are merely tools you can use but you will still have to figure out what would be the right tool or the right combination of tools for your specific case. Perhaps layered is good in one case and perhaps it doesn't bring anything to another case.
Optimization in general is very much an in-depth analysis and break-down of patterns specific to the scenario, that are then isolated and optimized. The process if often experiment, benchmark, re-adjust, experiment, benchmark, re-adjust, experiment, benchmark, re-adjust... of course experience reduce this process to a minimum but even with experience the specifics comes in a variety of combinations that still require some fine-tuning from case to case (given they are not identical).
Even if you find a good recipe for your current project it is not given that it will work optimal with your next project. This is one reason no one can give an exact answer to this question.
However, when it comes canvas what you want to achieve is a minimum of clear operations and minimum areas to redraw (drawImage or shapes). The point with layers is to groups elements together to enable this goal.

Is there an algorithm for positioning nodes on a link chart?

I'm a member of a small but fairly sociable online forum, and just for fun we've been plotting a chart of who's met who in real life. Here's what it looked like fairly recently.
(The colour is the "distance" from the currently-selected user, e.g., yellow is someone who's met someone who's met them. And no, I'm not Zak.) Apologies for the faded lines, they don't seem to have weathered the SO upload process very well.
It's generated as SVG, with a big block of JSON defining who's met who. The position (x,y) of each member on the chart is hard-coded into that JSON. Until now, it's been fairly easy to cope when someone meets someone else - at worst, maybe two or three people need to be shuffled around - but it does involve editing the co-ordinates manually. And now that the European and North American contingents are meeting up, and a few on the periphery are showing up at meets, all hell is breaking loose...
We can put some effort into making all the nodes draggable, which would make the job of re-arranging a bit less tiresome. But it seems more sensible to let the computer take care of positioning them, especially as the problem will only get harder with more members.
So, does anyone know of an algorithm for positioning these nodes on the chart, based on which other nodes they're linked with?
Ideally, it would
minimise or avoid long links
avoid having lines run underneath unrelated nodes
take account of the fact that well-connected nodes are bigger
do its best to show the wider "all these guys met each other" relationships (the big circle at the bottom is largely the result of one meet, for example, though the chart has no idea of when any two people met)
but if it gets us close enough to tweak it, that's progress.
And, what's the real name for these charts? I believe they're called "link charts", but I'm not getting good results from Google using that name or anything else I can think of.
We'll likely be implementing this in PHP or Javascript, but right now it's how to begin approaching the problem that's the bigger question.
Edit: Some great answers coming already. I would be very interested in the actual algorithm(s) used, though, as well as tools that do the job.
What you are looking for are f.e. force-based algorithms. There are quite a few libraries, and some have been named already, like prefuse, yWorks. Here a few more: jung, gvf, jGraph.
The real name for it is "graph". To generate graph, and have a good layout algorithm, the best is to use a software which will do the job.
I advise you to use Gephi.
This soft is able to do all the things you want to.
Have a look at the yWorks tools.
You can google for graph visualization. There are more libraries for this, including GraphViz, but probably not all your requirements will be met.
If you can deal w/ Java, take a look at prefuse.
Have a look at NodeXL
Also, this book may be relevant.

Is an algorithm to judge the age of person in a photo feasible?

My friend works for a non-profit organization working to stop the illegal exploitation of minors over sites such as craigslist.org, which is one of the more popular mediums. The question is whether or not it is possible, now or in the near future, to develop an algorithm to analyze a photo of a person and return a prediction of their relative age.
It sounds like a mammoth task. My only thought was some sort of Bayesian probability system. I know even people often have trouble judging someone's age but Bayesian spam filters are advertised as being "10 times as accurate as a human" so maybe it's possible?
I am pretty inexperienced though. I would appreciate it if someone else could suggest whether or not this is feasible and if so how and when?
EDIT: Thank you everyone for the responses. Smoore that study was very helpful but I think Hal's solution is the most practical for the time being.
Here's a possible (left-field) solution. Perhaps, you could tie it into some type of a captcha solution for the site itself. Prompt new users with images of other new users with the question: "Is this person over 18?". It's true that a 50% success rate is not a very effective captcha system, but it's a start.
Coupled with some other checks or repetitive checks and it could work. You could display the image to a number of new users, and base the result on a certain threshold. If, 8 out of 10 people flagged a certain image as not a minor, than it's probably pretty safe they are of age.
But, this whole system can be circumvented by simply uploading someone else's image so I'm not sure how effective any of this really is. :)
I expect it would be pretty hard to get right. Consider this set of photos where the same model is made up to look very different ages.
There are algorithm to reliably determine the attractiveness of a face. See acm.org and uni-regensburg.de. It wouldn't be too much of a stretch to imagine an algorithm which could predict age.
Characteristics such as smoothness would probably have a strong correlation with age. It would probably take a great deal of effort to be more reliable than your average carney though.
I think you would need some input from a forensic anthropoligist ( or at least an anatomist).
Differnet parts of the body grow at different rates so it might be possible to do something like size of head vs. shoulder width, arm length vs. body width.
Unfortunately it sounds like he is trying to differentiate between say a 14 year olds and 18 year olds. Which is only a four year difference, variations in genetic makeup and nutitrition would probaly give any system an accuracy of +/- 20% which would equate to three years for this age group.
On the other hand if you had a large sample of photos then you could account for the variance statisticaly and get a pretty good idea whether a site was likely to be exploiting minors systematicaly.
The direct answer to your question is that no, no such algorithm will exist in the near future, and is probably impossible to achieve with any accuracy without strong AI.
That said, a practical solution to your problem is probably the amazon mechanical turk:
http://mturk.com
There, you can pay a small fee to have real people complete a task for you. I'd probably set your task up so that you paid $0.02 to have a person estimate the age of maybe 5 faces at a time. You could double or triple check your results with other workers, particularly for those faces who seemed close to your age limit. This is probably your only practical solution other than hiring minimum wage interns to manually review all submissions.
Use mechanical turk
In this study they tried it by analysing facial geometry and wrinkle features. Problem is this would be affected by shot angle, lighting, etc.
In some theoretical sense it is probably possible. For all practical purposes though, it is currently impossible.
Mammoth is an understatement I think. "Giant glacier" or "moon" might be more appropriate.
This isn't to say it wouldn't be worth looking into but I have a feeling you'd be in for a lot of man hours before you came up with something remotely useful.
I don't think it's something that a computer could do with any degree of accuracy. It's even really hard for people to do. I mean, have you been the the liquor store lately, they are supposed to ask for ID from anybody who looks under 25 (drinking age is 19 here). Apparently some 40 year olds don't look old enough. Telling somebody's age just by looking at them is a very hard thing to do. Especially when you get into to erotic picture arena, where they are trying to make models seem younger than they really are.
I think you will also have difficulties with different composited pictures. For instance angles on a face, different lighting, as well as context and probably most of all... image quality/resolution. It's a lot easier to work with a 800x600 pic then it is to work with a 320x240. The algorithm is only as good as the subject.
I cannot see this approach (a software solution to measuring age) being very effective. I like the idea of users flagging images - a human being can discern age many times more effectively then any algorithm.
Practical approach aside, I'd advice against trying to develop anything in that direction for now.
Few reasons:
1. guessing someone's age is not a grateful task
2. "biological" age and "calendar" age of people vary greatly - I know people who are 30 and are still asked for an ID when buying liquor, and some who are barely 18 and already look over 30
3. some people's looks don't change over time - they just have that kind of looks
4. nowadays, everyone's working to look as young as they can - so basically, you've got the whole industry working against you :(
Anyways, to cut long story short, I don't think it's feasible for now.
A neural net is a reasonable approach, you would need a training set of pictures of people with known ages and a bit of image processing to remove hats etc.
edit: Question changed?
You might be ale to classify someone as 20-30 or 40-50 on a CCTV but you aren't going to be ale to tell if a model is 17 or 18 in a posed photo.
Just like nearly all advanced tasks in image classification this topic is still in research. Judging from this paper it is possible to do it but non-trivial, also you have to have a lot of (manually) annotated training data. Without any knowledge of this field and no experience in image processing this task is going to take you several months.
Develop a classification algorithm that bases a heuristic on many values of the pictures, amount of pixels that are dark within the face area (possibly wrinkles), and the color of the hair. These values should fall within a general area of any profile-esque picture, if you want to be fancy, carry weights with these values and develop a type of game tree that would be able to search hundreds of thousands of images quickly, finding where this image "falls" in the tree within an age-specific set of values.
Some Japanese cigarette vending machines do this. Not terribly well by all accounts, but then it probably doesn't matter since, as Hal mentioned, the easiest hack is just to use someone else's image...
Impossible is nothing, Only amount of efforts changes :
I think it would be near impossible if you target one particular feature of face.
you have to consider multiple factor, So decision will be lying in a matrix and you have to feed multiple things and you will get your answer i would enlist some feature :
1) Beard (Detect face , Now detect beard on face , Help full in distinguish male/female
/childern )
2) Hair
3) Wrinkles
4) Size of face
5) Ration between height and breadth of face
It would be a tough assignment but algorithm can be developed.
As of now, this is possible with 90% accuracy. Yes. please refer the following link..
http://www.omron.com/r_d/coretech/vision/okao.html

Predictive "blood glucose" algorithm?

I'm writing an app that lets a diabetic user enter his/her "blood glucose" readings, and then charts them on a graph over time from left to right. Since the blood readings will be done only several times a day, an algorithm would be handy to:
a) fill in the gaps on the graph between readings (curves would be more realistic than jerky lines) and allow a more accurate "blood glucose level" daily average
b) roughly predict what will happen in the future (if the user eats nothing that will affect his blood levels)
I suck at calculus. I'm hoping someone here knows a library for this stuff? I'm hoping someone knows of an algorithm that has been tailored for this specific problem already (e.g.: where someone has compared it to real data from diabetics)
Disclaimer: I am very aware that any such algorithm would vary wildly depending on the user. I'm just looking to improve on straight angular lines. Regardless of the diabetic, there is a limit to the rate that blood sugars can rise and fall.
I'm using Javascript, but as it's just math, I could port it from C, Java or whatever.
Blood sugar behavior is very complicated. It is affected by
Current blood sugar (complicated by the possible presence of ketones if the patient is hyperglycemic)
recent food out to several hours depending on the type and how much
recent fast acting insulin (with variety and patient dependent reaction profiles between 45 minutes and two hours long. Oh, and delivery mechanism)
long-acting insulin out past 12 hours (again patient and variety dependent)
activity levels
stress levels
illness
basal insulin rate if the patient wears a pump
ad nauseum
Very hard problem. Any heuristic---any heuristic---you chose would be highly misleading. So short answer:
Don't do it.
This comes, in part, from having compared a diabetic's 24-hour continous glucose log with the ~10 finger pricks taken during the same time. I.e. my suggestion is data driven.
Edit: Evidently I didn't make myself clear.
You can't even get close.
Nothing you can do with finger prick data can be remotely reliable.
Connecting the dots with any lines (even straight segments) is just plain wrong. It doesn't reflect reality. Not even a little bit.
I'm an experimental particle physicist. Complicated data sets are what I do. There is a diabetic in my life (did you guess?). This matters to me.
But I've seen the high frequency data logs, side-by-side with a log of the days finger-pricks, exercise, food, and insulin.
If you could get every-fifteen-minutes data, I'd say go ahead and use a spline. It won't be dangerously misleading. But, if you have 6-10 measurements across the day, you know nothing.
Good news: continuous monitoring is coming down in price. It's out of the lab and available with some pumps even now.
For those who aren't familiar with this: compliant diabetic patients do (results of extremely unscientific polling) 4-6+ glucose tests a day as a matter of course, and several additional ones in the 1-2 hours following any unexpected excursion (they get physical symptoms that allow them to detect severe excursions).
This serves to give the patient a rough idea of how they are doing at controlling their glucose levels, but they also go to a lab to get a Hemoglobin A1C drawn every quarter (or so). The A1C result is dependent mostly on their average blood glucose.
I've talked to people who clocked in a 80-110 (quite favorable numbers) four times a day for months, and got back an A1C suggesting an average above 150 (not desirable at all). Presumable they were going high in the night. And I've heard similar stories from people who we probably going low---very low---in their sleep.
The lesson is:
Finger prick readings have their place, but don't try to extrapolate them to times not well sampled.
If you want to do just a straight fit of the data to make things easier to view then something like what Charlie Martin recommended would likely work well. However, as noted by dmckee this data really wouldn't mean anything.
What you are trying to do is actually more in line with pharmacokenetics which is an entire scientific study in and of itself. In this case I'm not even sure it would entirely apply except in the case of Type I Diabetes as most of what I know about pharamcokenetics only applies drug studies, but if something is being produced by the body then you are likely looking at entirely different types of analysis. If you are interested in the subject then there are quite a few book previews on Google Books if you do a search for "pharmacokienetics" but due to the nature of the subject they are very math heavy and assume that you have an understanding of chemistry and biology as well.
okay, you're going to be looking for some fitted curve. The thing with that is that for n points there are fit polynomials up to order... n-1 I think. It's been a while. Yep. by golly, I'm right. The common thing when you have lots of points and don't wants a complicated function (which you don't) is to use a least-squares approximation.
probably the best thing is to look for a canned routine you can use; these exist in most stats packages. Give us a little more detail on the environment you want and we might be able to point you more closely to something suitable.
This is most likely not going to work but Artificial Neural Networks may, and i repeat may be able to get something out of a good data set. By good, i mean like weeks or months of continuous recording, and even then i wouldn't trust the data set unless i had very good reason to. I also don't think you'll get predictive data out of it, but it may depend on how you implement it. Overall if you were to do this it would seem to be more of a hobby thing to see if it even even come close, like "oh neat i got a neural network to within X amount of accuracy". Again, i must stress, don't use this in any sort of production situations or anywhere where it could possibly hurt or kill someone!

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