# On top of the world

I’ll be honest, usually I try to find a picture that fits in with the statistical message I’m trying to convey. But occasionally I see a picture and then look for a statistical angle to justify its inclusion in the blog. This is one of those occasions. I don’t know what your mental image of the top of Everest is like, but until now mine wasn’t something that resembled the queue for the showers at Glastonbury.

Anyway, you might have read that this congestion to reach the summit of Everest is becoming increasingly dangerous. In the best of circumstances the conditions are difficult, but climbers are now faced with a wait of several hours at very high altitude with often unpredictable weather. And this has contributed to a spate of recent deaths.

But what’s the statistical angle? Well, suppose you wanted to make the climb yourself. What precautions would you take? Obviously you’d get prepared physically and make sure you had the right equipment. But beyond that, it turns out that a statistical analysis of relevant data, as the following video shows, can both improve your chances of reaching the summit and minimise your chances of dying while doing so.

This video was made by Dr Melanie Windridge, and is one of a series she made under the project title “Summiting the Science of Everest”. Her aim was to explore the various scientific aspects associated with a climb of Everest, which she undertook in Spring 2018. And one of these aspects, as set out in the video, is the role of data analysis in planning. The various things to be learned from the data include:

1. Climbing from the south Nepal side is less risky than from the north Tibet side. This is explained by the steeper summit on the south side making descent quicker in case of emergency.
2. Men and women have equally successful at completing summits of Everest. And they also have similar death rates.
3. Age is a big factor: over forties are less likely to make the summit; over sixties have a much higher death rate.
4. Most deaths occur in the icefall regions of the mountain.
5. Many deaths occur during descent.
6. Avalanches are a common cause of death. Though they are largely unpredictable, they are less frequent in Spring. Moreover, walking through the icefall regions early in the morning also reduces avalanche risk.
7. The distribution of summit times for climbers who survive is centred around 9 a.m., whereas for those who subsequently die during the descent it’s around 2 p.m. In other words, it’s safest to aim to arrive at the summit relatively early in the morning.

Obviously, climbing Everest will never be risk free – the death rate of people making the summit is, by some counts, around 6.5%. But intelligent use of available data can help minimise the risks. Statistics, in this context, really can be a matter of life or death.

Having said that, although Dr Melanie seemed reassured that the rate of deaths of climbers is decreasing, here’s a graphical representation of the data showing that the actual number of deaths – as opposed to the rate of deaths – is generally increasing with occasional spikes.

Looking on the bright side of things though, Everest is a relatively safe mountain to climb: the death rate for climbers on Annapurna, also in the Himalayas, is around 33%!

In light of all this, if you prefer your climbs to the top of the world to be risk free, you might try scaling the Google face (though I recommend turning the sound off first):

While for less than the prices of a couple of beers you can get a full-on VR experience as previewed below:

Finally, if you’re really interested in the statistics of climbing Everest, there’s a complete database of all attempted climbs available here.