NSW

Charles 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'…
Charles 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…
Charles 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…
Your 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…
Alan 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…
What 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…
robert 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. -…
We'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…
My 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.…
I 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…
Frank 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…
Could 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…
Frank 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 (…
In 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…
Andy 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…