Benjamin Shuhyta writes: Geoff Walker (comments, Friday) makes two significant mistakes about rainfall and rooftops. Even assuming his estimates are close to the mark (200sq m per average rooftop, eight million rooftops) his basic calculation fails to carry enough zeros, and thus he comes up with 1,600 sq km, instead of 16,000 sq km. Second, he assumes that rainfall is evenly spread across the whole continent; and therefore mistakenly concludes that rainfall missed by rooftops is proportional to the landmass not covered by rooftops. Considering that 85 percent of the population lives within 50km of the coast, and considering orographic/coastal rainfall patterns, I would think that rooves covering 0.2% of the nation could actually be catching 10 times that percentage again in the nation’s total rainfall. I was ambivalent about the idea, but the more I look at it, the more attractive it seems.

John Carmody writes: Mr Christian Kerr and other political commentators need to be be a little more statistically informed when passing judgement on the results of opinion polling. The polls in question are binomial distributions: the sample data are processed to produce a “Two-party-preferred” outcome. In other words, the “raw” samples (with their multi-party primary choices) are being adjusted to such a binomial status i.e. one with only two possible outcomes. (This is like tossing a coin, with one outcome [say “heads”] deemed a “success” and the other [“tails”] a “failure”.) In such a distribution, the variability (measured as “Standard Deviation”, SD) is a function of the square-root of the number of observations and also of the probability of “success” and “failure”. With (approximately) 60% to the ALP (probability 0.6) and 40% to the Coalition (probability 0.4) and 1400 valid samples (the number of people who gave an unequivocal answer which is equivalent to the number of times the coin is tossed) this SD of the number of “successes” [here the estimated ALP vote] is 18.33 (distributed about that total of [840]). In most scientific experiments a 95% level of confidence is accepted (i.e. a 5% [or 1 in 20] possibility of error is deemed “acceptable”). For mathematical reasons, the spread then has to be about 2 SDs or, with the data to hand, about 36. Since 36 is 2.6% of the sample size (1400), we cannot be certain that a reported “difference” is “meaningful” if it is less than this. Since Mr Kerr refers to a “shift” of 2.5% in the putative “vote” for the ALP (and the Government), that is within the range of error and just less than would confidently allow us to claim that a “real” shift has occurred.

Carolyn Wood writes: I have to take issue with Adam Schwab’s comments about Andrew Demetriou’s pay, the AFL drug policy and blame. Correct me if I am wrong but I think AFL footballers are a group of the most privileged 600-odd young men in Australia with respect to the opportunities afforded them. They can have their education expenses paid for, their health monitored and supported, access to any business, education or personal support that they need when they need it and get paid a substantial commencing wage on which to do it. This is not to deny there are extraordinary pressures on such young men however I think there should be greater expectation of the role of AFL clubs as the primary employer of these players. Having boarded young AFL players in the past I know that clubs should do better in this area. It did not occur to me to ring the AFL when one of my boarders was having problems however the club concerned did next to nothing to help him and chose to ignore my repeated attempts to bring this to their attention.

John Ryan writes: The hysteria in Perth surrounding the WCE and Cousins has to be seen and heard to be believed, you have to wonder about the mental age of some of these people. The thing that interests me and which I have not been able to get a straight answer to, in spite of emails to radio talkback shows and phone calls, is where were the so called fearless sporting journalists that work for radio, TV and our one newspaper? This has been known about for about five years, but all we’ve got from our media is silence, cover up and more silence until now. This is from a bunch who jump all over other codes for the smallest infraction — considering Wendell Sailor is out for two years for taking drugs where does that leave Cousins and the AFL? But then listening to the commentary here in Perth, those nice middle class boys and the AFL can do no wrong, so it will be dropped, as one gentleman on one of the morning shows said “why are we even talking about this? It’s none of our business”. So it will be back to the usual AFL cover up.

Lynn Good writes: The sublimely witless Paul Lennon and the pulp mill he is desperately seeking exemplify the total cynicism of both the major parties selling us out to the logging industry. Subsidies to the Tasmanian logging business have been estimated at close to \$50,000 per worker p.a. at present, while a Victorian study estimated a \$1.00 return for every public \$2.50 spent on it. These figures don’t factor in costs of damage to the environment and to competing industries. You don’t need to be any brighter than the Tasmanian premier to work out what is going on here. The real mystery is how the public can swallow this scam, even with a bucket of midnight oil.

John Bowyer writes: John Lawrence (Friday, comments) talks about tax subsidy to MIS schemes, this is wrong. Tax is not avoided or the taxpayer given any sort of subsidy! The tax and the subsequent profit on the investment is deferred, that’s all. When the timber is harvested and the taxpayer takes his profit then the whole lot is taxed! Perhaps John would like to suggest another way of financing trees but don’t even think about us all living in caves in the hills and eating grass seeds as Gareth said the Greens wanted us to do John, please!

Gary Thomas writes: Re. Private equity conflicts. I fail to understand how the law can allow and support Directors and Senior management receiving tens of millions of dollars for “doing the job they are already paid to do by shareholders”. These private equity buyouts rely on the internal knowledge and support of Directors and Senior Company Management – surely a conflict of interest. I would have much more faith in their ‘independent’ assessment of what was in the best interests of shareholders if they did not receive any money whatsoever (other than what was available to any shareholder) as a result of a successful buyout. Of course, if this was the case, it would be hard to see many senior managers and Directors letting potential suitors “in the door” let alone receiving unqualified support.

Peter Wachtel writes: Re. The Future Fund. Interesting that during last Thursday’s Question Time the current Treasurer tabled a document outlining 10 times that Mr Swann has stated the Future Fund should never be allowed to be touched as he put it “A locked box”. Amazingly Kevin “Kenny Rogers” Rudd has decided that’s wrong and Mr Swann has now backflipped too. What’s more amazing that none of Crikey’s unbiased contributors mentioned it once! PS. Kenny Rogers as in the song “you gotta know when to hold’em, know when to fold’em, know when to walk away, know when to run…”

Niall Clugston writes: Liam Trehy asks (Friday, comments): “Is there actually a skills shortage or a shortage of employers paying market relevant rates?” The problem is that a market response requires: a voluntary readjustment of wages offered, a realignment of school students’ career plans, and the completion of an arduous trade apprenticeship. In other words, the market will response – a decade later. By which time there may well be an oversupply of tradespeople!

Peter Adams writes: Perhaps Helen Armstrong (Friday, comments) should first read a bird book before making uninformed statements about wedge-tailed eagles. The Slater Field Guide to Australian Birds states: “nesting — enormous stick nest in large tree”. Whether the eagle hunts in open grass land is irrelevant to the argument because if there is no habitat suitable to raise chicks, extinction is inevitable.

John Peak writes: Samantha Bowden’s defence (Friday, comments) of her use of “fortuitous” is odd: her original statement, “if one is fortuitous enough to get pre-selected for the Senate” clearly relates fortuitous, as an adjective, to a person, but her list of synonyms (today, lucky, fortunate, providential, advantageous, serendipitous, heaven sent) must surely be taken as referring to events. Which fortuitous does. Even the Oxford Dictionary will defend that.

Friday’s errors (house pedant Charles Richardson casts an eye over the howlers in the last edition of Crikey): Item 4: “… they also want to keep the pictures of flattened and burnt landscapes and poisoned wildlife as far away from themselves.” That “as far” needs something to keep it company – “as far as possible”, for example. Otherwise knock out the “as”.

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