**Reaction times – How fast are you?**

Go to the Human Benchmark site and test your reaction times. You have five attempts to press the mouse as soon as you see the screen turn green. You can then see how your reaction times compare with people around the world. According to the site over there have been over 15 million clicks – with a median reaction time of 251 milliseconds and a mean reaction time of 262 milliseconds.

We can see how this data looks plotted on a chart. As we can see this is quite a good approximation of a bell curve – but with a longer tail to the right (some people have much longer reaction times than we would expect from a pure normal distribution). In a true normal distribution we would have the mean and the median the same. Nevertheless this is close enough to model our data using a normal distribution.

From the data we can take the mean time as 255 milliseconds, and a standard deviation of around 35 (just by looking at the points where around 68% are within 1s.d)

So, with X ∼ N(255, 35²) we can then see how we compare with people around the world. Reaction times significantly faster than average would suggest an ability to do well in sports such as baseball or cricket where batters need to react to the ball in a fraction of a second.

I just tried this, and got an average of 272. I can work out what percentage of the population I’m faster than by doing the normal distribution calculation – which gives 31% of people slower than this. Trying it again gives an average of 261 – this time 43% of people would be slower than this.

Have a go yourselves and see how you get on!

**IB Revision**

If you’re already thinking about your coursework then it’s probably also time to start planning some revision, either for the end of Year 12 school exams or Year 13 final exams. There’s a really great website that I would strongly recommend students use – you choose your subject (HL/SL/Studies if your exam is in 2020 or Applications/Analysis if your exam is in 2021), and then have the following resources:

The Questionbank takes you to a breakdown of each main subject area (e.g. Algebra, Calculus etc) and each area then has a number of graded questions. What I like about this is that you are given a difficulty rating, as well as a mark scheme and also a worked video tutorial. Really useful!

The Practice Exams section takes you to ready made exams on each topic – again with worked solutions. This also has some harder exams for those students aiming for 6s and 7s and the Past IB Exams section takes you to full video worked solutions to every question on every past paper – and you can also get a prediction exam for the upcoming year.

I would really recommend everyone making use of this – there is a mixture of a lot of free content as well as premium content so have a look and see what you think.

## 4 comments

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March 26, 2015 at 7:42 am

kunsik11Reblogged this on Since 1997 and commented:

Try this out for yourself! It’s pretty cool.

April 20, 2016 at 11:17 am

AmyHow would you use this for an SL Maths IA? i.e. will a statistical investigation be enough to get a good SL grade?

April 20, 2016 at 8:29 pm

Ibmathsresources.comYes you can definitely do a statistical investigation for SL. You just need to make sure you go into more of the maths than for Studies. Some ideas – confidence interval testing, doing an experiment then trying to fit a curve to your data to compare it to the normal distribution, looking for relationships between age and reactions etc. Lots of possibilities.

December 27, 2016 at 6:37 am

RogerReaction times over 100 years ago were around 177 milliseconds. This, combined with a drop in attention span from 2000 until now from 12 to 8 seconds suggests we are getting more stupid.