Tuesday 10 April 2018

Quibans 85: Crime and Police figures

From the Cambridge News:


Violent crime in Cambridge has nearly doubled in a decade as police numbers drop
9 APR 2018
Bottom of Form
Violent crime is 90 per cent higher than nine years ago, while police officer numbers have dropped by nearly a tenth.

In Cambridgeshire, there were 15,975 violence against the person crimes reported in the year to September 2017, the latest figures, a ## per cent rise from 8,364 reports in the year ending September 2009. 
However, over the same period, the full-time equivalent number of police officers at the force has fallen by ## per cent, from 1,438 in September 2009 to ## in September 2017, a loss of 106 officers. 
In the past year alone, Cambridgeshire has seen a 30 per cent rise in violent crime, up from 12,316 cases, while police officer numbers have dropped by 1 per cent or seven officers.
A police spokesperson said: “Some of the increases in violent crime can be attributed to improving recording standards and increased reporting of domestic abuse. Most violent crime happens behind closed doors rather than on the streets and the force is working hard to reduce all violent crime.”
Across England and Wales, there was a 20 per cent rise in violent crime, made up of violence against the person, both with and without injury, and homicide, in a year.
In the year ending September 2016, 1.08m violent crimes were reported, rising to 1.29m in the year ending September 2017. 
Compared to the year ending September 2009, when there were 706,859 reports, numbers have more than doubled, a 114 per cent rise, according to figures from the Office for National Statistics, with most forces seeing low in the number of reports in 2012 or 2013.
Over the same period, police forces across England and Wales have lost 22,155 officers, a 15 per cent drop in numbers between September 2009 and September 2017, according to Home Office figures. 
Numbers have dropped by 1 per cent in the past year, from 126,252 full-time equivalent officers in September 2016 to 125,364 in September 2017, a loss of 888 officers.

Questions:
1)      Work out the missing numbers (shown by ## in the text above).
2)      Is the subheading reasonable?  (Violent crime is 90 per cent higher than nine years ago, while police officer numbers have dropped by nearly a tenth.)
3)      Are the other figures in the article consistent?  (Hint: they aren’t!)
4)      How does Cambridgeshire compare to the national situation?




Answers:
Q1)  From the article:
In Cambridgeshire, there were 15,975 violence against the person crimes reported in the year to September 2017, the latest figures, a 91 per cent rise from 8,364 reports in the year ending September 2009. 
However, over the same period, the full-time equivalent number of police officers at the force has fallen by 7 per cent, from 1,438 in September 2009 to 1,332 in September 2017, a loss of 106 officers. 
Checking this:  15975 ÷ 8364 = 1.90997, which is a 90.997% increase.  91% is accurate.
1332 ÷ 1438 = 0.92629, which is a 7.4% decrease.  7% is accurate.

Q2)  The subheading says:
Violent crime is 90 per cent higher than nine years ago, while police officer numbers have dropped by nearly a tenth.
91% has been rounded to 90%, which seems fine.  7% from the article has become “nearly a tenth” in the subhead.  That seems a little out given that it is a way away from 10%.  If both numbers have been rounded to the nearest 10% then …
2009 is eight years before 2017.  The heading says “nine years ago”.  Perhaps they are referring to 2009 being eight years ago from now, but that seems a bit odd, given that we don’t know what the current figures are for 2018.

Q3)  From the article:
In the past year alone, Cambridgeshire has seen a 30 per cent rise in violent crime, up from 12,316 cases, while police officer numbers have dropped by 1 per cent or seven officers.
We have, from earlier in the article, 15,975 violent crimes.  15975 ÷ 12316 = 1.297, which is a 29.7% increase.  30% is fine.  There are now 1332 police officers.  The percentage is 1332 ÷ 1339 = 0.99477, which is a drop of 0.52%.  This has been rounded (unfairly?) to 1% 
A police spokesperson said: “Some of the increases in violent crime can be attributed to improving recording standards and increased reporting of domestic abuse. Most violent crime happens behind closed doors rather than on the streets and the force is working hard to reduce all violent crime.”
This is important.  The article refers to ‘recorded crimes’, so those that aren’t recorded aren’t included and it could be the case that there aren’t in fact more crimes being committed, but rather more crimes being reported.  It would also be worth comparing the increase in crimes to the increase in population (but only for particular age-groups?).
Across England and Wales, there was a 20 per cent rise in violent crime, made up of violence against the person, both with and without injury, and homicide, in a year.
In the year ending September 2016, 1.08m violent crimes were reported, rising to 1.29m in the year ending September 2017. 
1.29million ÷ 1.08million = 1.1944, which is an increase of 19%.  This has been shown as 20%, but it is possible that the accurate value is in fact 20% and rounding issues have intervened.
Compared to the year ending September 2009, when there were 706,859 reports, numbers have more than doubled, a 114 per cent rise, according to figures from the Office for National Statistics, with most forces seeing low in the number of reports in 2012 or 2013.
I can’t make this one work at all.  There are now 1.29 million reports and there used to be 706,859.  Clearly this isn’t more than double.
Over the same period, police forces across England and Wales have lost 22,155 officers, a 15 per cent drop in numbers between September 2009 and September 2017, according to Home Office figures. 
Numbers have dropped by 1 per cent in the past year, from 126,252 full-time equivalent officers in September 2016 to 125,364 in September 2017, a loss of 888 officers.
125364 ÷ (125364 + 22155) = 0.8498, which is a drop of 15%
125364 ÷ 126252 = 0.992966, which is a drop of 0.7%

Q4)  I’ll leave it to you to compare the numbers …




Thursday 5 April 2018

Quibans 84: xkcd

There are lots of classic xkcd cartoons.  This one is a Core Maths problem!



Question:  How many apples have you eaten in your life?


Source: https://xkcd.com/1976/ 

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