NSW
tlambert | November 22, 1997Charles Scripter wrote:
Here we fit the NSW "before" region to a slope + constant background,
while the "after" region is fit only to a slope (chance resulted in
this slope passing through, or very close to zero, eliminating the
need for a constant, 4th parameter). The origin is located at year 1900.
Data for years 1919 and 1920 were rejected as "anomalous" and the
"before" region was extended back to 1907 to offset this loss of data.
It is amazing what you can show if you pick the right subset of the
data. In particular, if you want to "find" a decreasing trend, just
follow Charles'…
tlambert | October 28, 1997Charles Scripter wrote:
[...regarding Tim Lambert's assertion of a significant decrease in homicide
in New South Wales in 1920, coincident with the enactment of a gun control
law in NSW in that same year...]
The Lambert analysis method
clearly shows that there was a significant decrease for any year one
may choose, from 1910 to 1930.
The statistical test shows that we can reject the null hypothesis of no
change in the homicide rate in NSW between 1910 and 1930. Because the
change is so highly significant, it also possible to reject the same
null hypothesis by putting a step at other years…
tlambert | August 4, 1996Charles Scripter writes:
BTW, I notice that your web page still seems to purport that your
analysis was correct, even though your friends over in sci.stat.edu
pointed out that it was not correct;
That's an interesting interpretation of the discussion.
Perhaps you'd like to correct this "oversight".
No problem, here's something from one of my friends in sci.stat.edu:
Barry McDonald writes:
THE ARGUMENT ABOUT AUTOCORRELATION IN THE NSW HOMICIDE STATISTICS
One complaint by Scripter about your data was to do with the evident
autocorrelation in your data. It was this that was of interest to me…
tlambert | October 17, 1992Your claim that I have not shown that the situations were
stable is false. The homicide rate was roughly constant in the period
before gun control and in the period after gun control.
Andy Freeman said:
The graphs have shown that it was roughly constant AFTER, but before....
there was a dip in the period 1915-18, associated with WWI and
fluctuations before 1905.
It might be that demographic change caused the decline i.e. a
decrease in the percentage of young men in the population. However,
the demographic change associated with WWI when 40% of the males 18-45
enlisted, is far far larger…
tlambert | October 16, 1992Alan Watt said:
However, what effect did WW-I have on the age-distribution of the population?
I would expect the percentage of 18-25 year-olds in the general population
to be reduced due to war casualties. In the U.S., this is the age group
which accounts for most of the violent crime.
Here are the percentages of the population of NSW that were between 18
and 25 inclusive at each census year:
Male Female
1911 8.4% 8.2%
1921 6.4% 7.1%
1933 7.3% 7.0%
This suggests that the male percentage would have been 7.4 in 1921 were
it not for the Great War. However, I…
tlambert | October 14, 1992What on earth do you mean by 'the "nothing else happened"
parameter"?
Andy Freeman said:
Lambert's model is for a transition between two stable situations with
some "noise". He uses it to argue that gun control explains the
transition. Yet, he doesn't bother to show whether or not anything
else happened at the relevant time, whether or not the situations were
in fact stable, and so on.
You call this a "parameter"?? This is a bizarre usage even by your
standards. Your claim that I have not shown that the situations were
stable is false. The homicide rate was roughly constant in the…
tlambert | September 18, 1992robert i kesten said:
Could you give the date(s) and an 11 year (5 before, first year
of implementation, 5 after) table of homicide rates. If possible
I'm interested in Australia as a whole, not just NSW or any other
state.
Here are the states for which I have data.
(Data for WA and Tas are
incomplete in ways that make them useless for evaluating gun laws.)
Qld and SA figures come from "Source Book of Australian Criminal & Social
Statistics 1900-1980" Mukherjee. Victoria from "Victorian Year Book"
volumes for 1901,1902,1903,1904, etc. NSW from "Homicide:The Social
Reality" Wallace. -…
tlambert | September 17, 1992We've been around on this before, and all it does is impress me with
the predilection of some pro-gun folks for self-delusion on this
topic. (I'm sorry if that sounds harsh, but it seems to me that many
people suspend their powers of reason on this issue.)
Here are the NSW homicide rates from 1910-1920:
2.6 2.7 2.4 2.1 2.4 2.6 2.1 1.9 1.4 2.7 2.7
Care to demonstrate a decline?
Geoff Miller said:
What can be demonstrated very easily is that you are supporting your own
position with some very carefully chosen figures.
Untrue. Frank Crary claimed that there was a decade long decline,
ending…
tlambert | February 5, 1992My model has two parameters (pre 1920 rate, post 1920 rate).
Your model has four parameters (starting rate, first decrease, second
decrease, year that rate of decrease changed). The more parameters
that your model has, the easier it is to fit the data.
Frank Crary said:
However, no one is restricting the number of free parameters in your
model, except yourself: You are (or were) using this data to support
your assertions that: The homicide rate in New South Wales dropped
suddenly after the introduction of gun control laws in 1920, and that
there was no pre-existing trend toward lower rates.…
tlambert | January 28, 1992I was able to find some statistics on homicides in South Australia (in
"South Australian Historical Statistics" Vamplew, Richards,Jaensch and
Hancock)
Unfortunately, they only cover the period 1921-1979, but we can use
them to see if gun control, introduced in SA in 1929, had any effect.
We can use the adjacent state of NSW as a "control". The SA homicide
figures include "manslaughter by driving" and the NSW figures do not,
so they are not strictly comparable, but before 1940 they were only
two or three cases of manslaughter by driving each year in SA.
The second last column is the…
tlambert | January 27, 1992Frank Crary said:
In an effort to clear up this statistical game, I'm posting a detailed
comparison of Mr. Lambert's and my models of the crime rate in New South
Wales, between 1910 and 1930.
The data, taken from the graph he posted on the 15th of this month, is:
[Numbers deleted]
(Please correct me if I'm in error, Mr. Lambert's ascii graph reached me in
a slightly garbled form.)
Eeek! About half of those numbers are incorrect. I guess ascii
graphs are not the most robust ways to transmit information. I have
appended the correct numbers to the end of this posting, so that my
calculations…
tlambert | January 26, 1992Could the changes be caused by noise? This calls for a t test, to see
if the average homicide rate changed.
Andy Freeman said:
There's an interesting thing about averages. If you take the average
of a declining series and compare it to the end point, you find that
the average is, not surprisingly, higher.
Lambert's stats show that the pre-control rates were decreasing.
Were the pre-control rates decreasing?
NSW average homicide rate
1901-1910 2.3
1911-1920 2.3
There certainly is no long term trend. Perhaps there is a short term
trend:
NSW average homicide rate
1912-1914 2.3
1915-1917…
tlambert | January 20, 1992Frank Crary said (referring to changes in homicide rate in NSW and Qld):
The sharp drop you claim to see, is (in my opinion) not significant compared
to the background variations. While this may have been real effect of gun
control laws, in is at least as likely that it is a coincidence.
Could the changes be caused by noise? This calls for a t test, to see
if the average homicide rate changed.
The significant events were:
1920: NSW controls all guns
1927: Queensland controls handguns and NSW drops controls on long guns
So, I took three groups of years 1911-1920 (pre-control), 1921-1927
(…
tlambert | January 15, 1992In a previous posting I observed that the homicide rate in New South
Wales fell dramatically following the introduction of gun controls in
1920.
Here, again, is the graph showing the homicide rate in NSW from 1900-1977.
(Vertical scale is homicide rate per 100 000 population)
3 *
2.8
2.6
*
2.4 *
2.2 *
2.0 * * *
1.8 * * * * *
*
1.6 *
* * *
1.4 *
* *
*
* *
1.2…
tlambert | December 21, 1991Andy Freeman said:
Why doesn't Lambert tell us about pre-control crime and murder rates
and trends in Oz and compare them to post-control rates and trends?
If gun control actually worked in Oz, the introduction of controls was
associated with a good change in the rate trend. Could it be that
there wasn't a good change associated with the introduction of
controls?
"Homicide: The Social Reality" by Alison Wallace, published in 1986 by
the NSW bureau of Crime Statistics and Research is an extensive study
of all homicides in NSW from 1968 to 1981. This contains a graph
detailing the homicide…