Archive for the ‘statistics’ Category

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Lies, Damned Lies and Breast Surgery

May 20, 2013

Angelina Jolie has had both breasts removed because of the risk of developing breast cancer.

Angelina

But did she understand the Maths?

She may be right. This could be the best way for her to avoid breast cancer. And it IS her decision.

bow

But maths isn’t that clear cut. Referenced information about BRCA1 and BRCA2: Cancer Risk and Genetic Testing can be found at The National Cancer Institute here.

More information from the UK NHS here.

bowThe estimates of lifetime risk are about

12.0 percent of women (120 out of 1,000)

in the general population will develop breast cancer sometime during their lives compared with about

60 percent of women (600 out of 1,000)

with gene mutation in BRCA1 or BRCA2. This is FIVE TIMES the risk over a lifetime.

Breast Cancer stats

BUT and this is a big but …..

It is important to note, however, according to The National Cancer Institute (USA), most

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research related to BRCA1 and BRCA2 has been done on large families with many individuals affected by cancer and the cancer risk associated with BRCA1 and BRCA2 mutations have been calculated from studies of these families. Because family members

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share a proportion of their genes and, often, their environment, it is possible that the large number of cancer cases seen in these families may be due in part to other genetic or environmental factors.

Factors that could affect these risk factors include food, lifestyle, location, inherited temperament and even the air they breathe. bow

Statistics are a useful tool. But statistics are based on random selection. This is IMPORTANT. Once you bias the data, your results are corrupted.

Removing cancerous breast tissue makes sense. Removing perfectly healthy breast tissue based on the maths … well … you’d want to think about it.

To put this another way the BRCA genes may be correlated with breast cancer, but this event is not independent of all other events in one family. There may be many, yet to be discovered, links . This is a common error in statistics made not only by journalists, but by experts too. (See below)

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Conviction by Maths Error

sally-3

On 9 November 1998 at Chester Crown Court Sally Clark, a Cheshire solicitor, was convicted, by 10-2 majority, of smothering her two baby boys.

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Clark’s first son died suddenly within a few weeks of his birth in 1996. In 1998, when her second son died in similar circumstances she was arrested and tried for the murder of both sons.

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The prosecution used paedeatrician Prof Roy Meadows as a expert witness. He had discovered Munchausen Syndrome by Proxy (MSbP). Sally Clark was found guilty and spent 3 years in jail.

observer-sally-clark

Prof Roy Meadows testified that the chance of two children from an affluent family suffering sudden infant death syndrome was 1 in 73 million. He arrived at this number by squaring 1 in 8500 for likelihood of a cot death in similar circumstances.

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He was wrong and was later struck off the medical registrar. He assumed that these were independent events. They were not. Maybe the heater was at fault. Or the cot. Or the house paint. Or, as suggested in The Observer article, faulty genes in the family.

Sally Clark died several years later of alcoholic poisoning. More information.

 

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500,000 Hog Hits

April 27, 2013

Mathspig is sooooooo excited

about reaching:

5 etc hits

To celebrate 500,000 or 5×105 hog hits

 and to continue showing mathspiggies everywhere

that maths is fun

and relevant to all

Mathspig presents

The MATHEMATICAL

CABINET OF

500,000

CURIOSITIES!!!

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1

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If you took a sample of

500,000 US teens

how many DO YOU THINK fall

asleep at school

at least once a week?

asleep

You will find amazing US teen stas here:

28% report falling asleep once a week

 500,000 x 28/100

= 140,000

Snoring to the left of you. Snoring to the right of you. You are not alone.

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happy-2nd-birthday
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What volume of coke is there in 500,000 cans?

coke shower

Coke can vol = 355 ml = 12 fl oz

500,000 x 355 = 177,500,000 ml

= 177, 500 l = 177.5 m3

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An average bath uses 150 litres water per bath.

How many bathtubs would 500,000 cans of coke fill?

177,500/150

= 1,183 baths in coke!!!

Hey mathpiggies, wanna bubble bath? You’d be tickled pink.

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3

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In a crowd of 500,000 how many people

would have their birthday

on the same day as yours?

bd cake

There are 365 days in the year so the probability of anyone having their birthday on the same day as you (ignoring leap years) is:

1 in 365 or 1/365.

 

In a crowd of 500,000 the number of people who have a birthday on the same day as you is most likely:

500,000 x 1/365 = 1,370

That’s a lot of birthday cake!!

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4   How heavy is $500,000 dollars?

 money bag

Australia:

$ Aus

Wt Aus $1 coin = 9.0 g

If the bank gave a bank robber $500,000 in $1 coins it would weigh:

500,000 x 9.0 = 4,500,000 g

= 4,500 kg = 4.5 tonne

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UK:

UK [pound coin

.

Wt UK £1 coin = 9.5 g

500,000 x 9.5 = 4,750,000 g

= 4,750 kg = 4.75 tonne

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USA:

$ usa

Wt US $1 coin = 8.1 g

500,000 x 8.1 = 4,050,000 g

= 4,050 kg = 4.05 tonne

You will find all you need to know about the size and weight of US coins and notes here.

$500,000 in $1 notes would only weigh

11 lb or 5 kg.

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So, um, bank robbers do the maths!!!!!!!!!!!!!!!!!!

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How far would you walk in 500,000 steps?

We’ll assume you take a big step of 1m.

step

So 500,000 m = 500 km.

A comfortable walking rate is 5 km/hr.

How long would it take you to walk 500 km without a break?

500/5 = 100 hrs.

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6 049_tns6 bugatti-veyron-super-sports-480

The Bugatti Veyron Super Sport  hits a maximum speed of 267 mph (429 km/h).

How long would it take the Bugatti travelling at top speed – not including refueling time – to clock up 500,000 km?

500,000 /429  = 1165.5 hr

= 48.5 days

The speed of an average sized commercial passenger plane ≈ 500 mph 0r 800 kph or

≈ twice the speed of the Bugatti.

So it would take a passenger plane approx 24 days to travel 500,000 km.

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7 A&E

How long would it take you to count to 500,000?

kid counting

Assuming you count at the rate of 1 per second the time it would take is 500,000 seconds.

500,000/ 60 = 8333 mins = 833/60 hrs

= 13.88 hrs or 13 hrs 53 mins

Come on! You could do that mathspiggies!!!!!

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8gloom

 In a group of 500,000 US teens how many are serious cave dwellers or, to be more accurate, how many spend less than 3 hrs a week outdoors?

It is an amazing 30.1%.

500,000 x 30.1/100

= 150, 500 creatures of the gloom.

Come on you teen gloomagogs get outdoors. You need the sun. You need the Vitamin D.

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9m&ms

How many calories in 500,000 m&ms?

There are an amazing 400 million m&ms produced everyday in the US. One m&m weighs 0.7g.

And calories in 1 m&m =  3.4 cal

500,000 m&ms weigh:

500,000 x 0.7 = 350,000 g

= 350 kg

As 400 million or 8 x 500,000 m&ms are produced each day, that is 8 x350 kg or 2800 kg or 2.8 tonne.

Calories in 500,000 m&ms is:

500,000 x 3.4 = 1, 700, 000 Cal

m&m kid

As the average consumptionof chocolate in the US is 5.18 kg per year eating 500,000 m&ms would take:

ranking_of_consumption_chocolate_2007

350 kg/ 5.18 kg

= 67.6 years!!!!!!!!!!!!!!!!!!!!!!!!

You better get going!!!!!

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10ablink

Blink rates vary but the average blink rate in a laboratory setting for a human is 10 blinks per minute.

How long would it take for you to blink 500,000 times?

500,000/10 = 50,000 minutes

= 50,000/60 hrs = 833.3 hrs

= 833.3/24 = 34.7 days

= 34 days 17 hrs 17 mins

But don’t think it or you’ll go blink crazy!!!!

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iPod Shuffle: Don’t Play It Again Sam

February 18, 2013

iPod shuffle

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Guess, what Mathspiggies?

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When Apple first released the iPod Shuffle it included a Random Play option from the owner’s playlist. People started complaining that ‘random ‘ option played the same track in a row or too often. Why?

Because random means any track is selected then that track goes back on the list and may or may not be selected again. To correct the ‘RANDOM’ problem Apple had to add an algorithm that stopped to many repeats.

See Fun Class Exercise to check RANDOM PLAY here.

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Trick 9: The Mentalist Vs The Mathematician Slapdown

November 30, 2012

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Mentalist Vs Mathematician Slapdown

Requirements: A coin for each student & smart board or data projector.

First ask your students to toss a coin 10 times each.

Ask each student how many heads in a row they threw.

Now ask students ‘Do you think it is possible to throw 10 heads in a row?

It can be done. Here is how you do it.

Derren Brown is a UK mentalist, magician, hypnotist and maths guru. He’s awesome. He shows audiences how a lack of understanding maths, especially probability, leads to misinterpreting the facts.

Now play this video to the students:

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The Hunger Games Maths

April 11, 2012

The Hunger Games is about MATHS. Here are some interesting Hunger Game statistics.

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THE PLOT:

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In Suzanne Collin’s book, The Hunger Games, 12 districts in the land of Panem are suppressed and controlled by a vicious elite, who dress like neon-coloured French courtesans.

Each year the cruel rulers select one teen of each sex between the ages of 12 and 18 from each district to become tributes, who must fight to the death in a televised, sponsor-supported media event called The Hunger Games, set in a staged wilderness.

Only one tribute can survive. Katniss Everdeen and Peeta Mellark from the poor coal-mining District 12 are the local tributes for that year and must play at being star-crossed lovers to gain sponsor support and survive.

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THE MATHS:

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……………………………………………….……..The Reaping…..


Tributes are selected in a process called The Reaping. The names of the, approximately, 2,000 young people in each district are placed in separate barrels for males and females and the names are drawn out of these barrels BUT…

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12 year olds …….. 1 slip

13 year olds ……..  2 slips

14 year olds ……..  3 slips

15 year olds ……..  4 slips

16 year olds …….. 5 slips

17 year olds ……..  6 slips

18 year olds …….. 7 slips

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BUT you can gain extra ‘food’ if you accept for more name slips.

Gale Hawthorne (pictured above), Katnis’ friend from District 12, has 42 slips in the barrel. What are his chances?

We will assume that there are 1,000 teens of each sex in each district and an equal distribution – rounded off – for each age group to 1000/7 = 143

 

 

Age Group

Name slips

Total Name Slips

Probability of being REAPED

Probability

P

12

1

143

1 : 4004

1: 4004

13

2

286

2 : 4004

1 : 2002

14

3

429

3 : 4004

1 : 1335

15

4

527

4 : 4004

1: 1001

16

5

 

715

5 : 4004

1 : 801

17

6

 

858

6 : 4004

1 : 667

18

7

 

1001

7 : 4004

1 : 572

total

 

 

4004

 

 

 

 

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12 minute Maths Guru

July 4, 2011

Meet Salman Khan. He has put free maths on-line.

This article on Salman appeared in The Sunday Times, UK, 12 JUN 2011.

Salman, 28, started putting tutes online for his 12-year-old niece, Nadia, and things grew. So far the Kahn Academy’s claim to fame are:

* Over 2,400 videos including hundreds and hundreds of 12-minute maths tutes

* Over 63,000,000 lessons delivered.

* Bill Gates kids use the site.

* A staff of 1 with funding from The Bill and Melinda Gates Foundation.

* Tutes on Biology, Chemistry and Physics too.

You can look up the maths tutes by topic @ The Khan Academy.

Or search topics on Youtube eg. Introduction to Conics Khan

Why Does Mathspig like The Kahn Academy? Because it’s:

1. Free.

2. Quick

3. Clear

4. Low-key

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Salman gives digital chalk-and-talk tutes like a teacher. He hand draws the equations and graphs. He uses a calculator from time to time, but he tends not to use whizz bang spreadsheet graphs or perfectly presented textbook equations. It’s a bit wobbly and it’s all coming from Salman’s head.

And students like this approach. It makes maths look do-able.

Go, Salman.

Mathspig thinks you are just GORGEOUS!!!!!!!!!

 Australia’s Year 7 – 12 Maths Curriculum is already on-line and free, funded by McDonald’s. See What are maths teachers for, sir?

The tutes on Maths Online are produced by Aussie Maths teachers and they are very good. Mathspig, of course, imagined the quadratic function tutes might look something like this:


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1. Hat Wearers Wear Hats

October 12, 2010

Statistics

The SELF SELECTING SAMPLE.

(Thanks Ivy for the No 1 rocket.)

Newspaper and magazine editors urge their readers to ‘click-on our website poll’ and then they publish the results in the next issue. The newspaper may learn about their readership. This is useful information for marketing but otherwise useless. It’s like asking hat wearers if they wear hats. Let me guess the answer? D’uh!

Included here are some results of two self-selecting surveys, which not only reveal the standard useless statistics but also some highly questionable numerical outcomes. In the Esquire Magazine Survey of Drinking (Sept 2010)  82% of their readers, who were willing to answer a survey about their drinking habits (Whereby, for some reason. 1 beer = 2 drinks), have a University Degree or higher (Or, maybe, 50% of them lie!!!!) and in the Health and Fitness (Oct 2010) magazine survey  - Guess what? – magically the numbers for all options add up to 100%. Neat! Didn’t anyone fit more than one category? (Assuming all readers of Health and Fitness mag who are bothered enough to answer a survey on fitness do some exercise.)

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2. My Mum Says Survey

October 12, 2010

Statistics

The SMALL SAMPLE error.

A survey is taken but the number of people surveyed is so small as to be irrelevant; not much better than simply asking your mum for her opinion and publishing the results.

Included here is a full-page Women’s Weekly (Oct 2010) ad for an Elizabeth Arden Anti-wrinkle Cream. Look at these wonderful statics. 92%… 85% …Wow! Look at the language. Gives eyes a ‘radiant and luminous look’ Sounds like the DEVIL!!!! Read the small print.

The survey was based on 30 participants and ‘results may vary’.

                            

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3. The Trouble with Double

October 12, 2010

Percentages

When the Numbers involved are so SMALL the % Stated is Meaningless.

Newspapers often state that a cancer rate has doubled or increased (See pic) by 28%. Those % changes can be meaningless. For instance, double nothing is still nothing. You need the actual numbers.

 

Here is a statistic taken from Men’s Health magazine (March 2010). According to the government funded Australian Institute of Health and Welfare the actual number of Australian males who presented with melanoma in 2005 was 6,044

or   0.549  in 1,000

or 1 in 2,000.

If these numbers increase by 28% the number of Australian men presenting with melanoma will be:

 

0.703 in 1,000

or  ~ 2 in 3,000.

These numbers are not so alarming. Then again would you take any notice of statistics of a magazine that suggests a ‘sonic boom’ from a golf club is causing deafness!!!!!

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4. NO. 26 It’s Your Turn Tonight

October 12, 2010

 Probability.                                          

Independent Events are not RELATED.

Lotto draws are, as with coin flipping, Independent or UNRELATED EVENTS. Newspapers often publish the least drawn numbers prior to a major prize draw.

When on June 5 2008 the Powerball jackpot reached over $50 million, making it the biggest prize ever offered in any Australian lottery game at the time media commentators went crazy. ( See Crazy Lotto Lovers Go Bananas Again!)

The Today show on Ninesmsn website advised ‘The most-drawn Powerball numbers are 26, 22, 5, 39, 24 and 34. The least drawn numbers are 41, 32, 10, 43, 35 and 20.’ This information is worthless. These facts imply that the balls know whose turn it is and then can organise themselves so that those balls drop down the shoot. As if! The draw is random. Any number is possible.

The winning numbers, in drawn order, were: 5, 21, 11, 38 and 2, with the Powerball 33, with the final prize of $58,737,207.41

Poor old 41, 32, 10,43, 35 and 20 will have to wait for another turn!!!!!!!

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