Pro challenges News survey Dear Editor: As a professional in the area of statistics, perhaps | can shed some light on the dispute between your newspaper and Gordon Gibson over the accuracy of the public opinion poll published January 16. Polling accuracy depends not on the proportion of the population that is surveyed, but on the absolute number in the completed sample. Hence, the Gallup Poll (sample size about 1,030) is considerably more accurate than the News poll (overall sample size 287 after refusals), even though the latter takes in a_ larger fraction of the relevant population. To assess Gibson's claim that he is ahead on the North Shore and that Cook may be running third in the riding as a whole, one must compute the sampling errors in the News survey. For reference, eo No library cuts Dear Editor: . It was with surprise and annoyance that I learned that the West Vancouver Council plans to reduce the Memorial Library budget by an effective 20% plus. A 14% decrease from last year and no allowance for in- flation. This can only result in an umacceptable reduction of library opening hours and service. As a regular user of the Memoria! Library I strongly protest this reduction in expenditure. If other readers feel the same way. I recommend they phone or write the Mayor and council as I have done. P.M. Stephen North Vancouver KEEP [T SHORT Readers’ letters on all topics are welcomed and MAILBOX wants to print as many as possi- ble, subject only ta space limitations. To heip us print YOUR letter while it's still time- ly, please keep it short and to the point-normaily no longer than 200 words (about 20 tines of average typing or 26 lines of average handwriting). All letters must be signed and include an address = andior phone number. The writer's name must also be spelled out clearly in block letters. Street addresses and phone numbers will not be published, and a nom-de-pilume will be used if specialty requested. We reserve the right to edit letters tor brevity, taste and legality. Let s hear from you — often The address 1s North Shore News, 1139 Lonadale Avenue, North Vancouver, B.C. V7M 2H4. OFFICE PERSONNEL Mieawens Aa . eo ~ Maureen Stirling Sylvia Gowans PERMANENT TEMPORARY Oe assist ASSISTANCE for Key Personnei 107? 140 WwW 156 Street North Vancouver 984-0251 note that the errors in the total Gallup Poll are on the order of plus or minus 2 percentage points. Mr. Gibson’s popularity might be as high as 37.7%, and Mr. Cook's as low as 29.4%. Such is the thtoretical margin for error, namely, 10.4-11.5% plus or minus. If the News survey is geographically balanced, as ‘Claimed, and if refusals were evenly distributed, then the sample of decided voters in North Vancouver-Burnaby should have numbered about 65-75 as a rough guess. (At this level, 10-15 either way would not upset any of the It follows that Mr. Gib- son's first claim is entirely consistent with the evidence, properly interpreted, and that his second claim could also be true, since the NDP candidate might stand as qualitative conclusions high as 32.9%. which follow). A_ few minutes with a hand Richard D. Scott, Ph.D. calculator and knowledge of the appropriate formulae are enough to show, on the basis of the published figures, that North Vancouver (The News queried Mr. Richards on two points in his Long Gowns Values $32 to $54 $Q99 Bianca & White Stag Co-ordinates Values $30 to $75 Lecce eee e ee 50 % off TanJay Co-ordinates Values to $20 to $50 $1499 _ $9499 3D Co-ordinates Values $46.00 10 $80 $9499 _ 59999 Dresses $1999 Values $48 to $70 Surrey Classics Co-ordinates Values $35 to $60 .. $999 — $3999 Sportswear Mond Co-ordinates Values $60 to $100 £399 59699 - 539°? Coats Values $85 to $380 Branches in Burnaby * Door Busters Prince George - letter which we felt readers might wish to have clarified. We asked him to define “absolute number” and also to explain why accuracy does not depend on the relationship of sample size to population. Mr. ards provided a large amount of complex scientific data couched in terms in- comprehensible to a layman but also cenceded the following: (1) “There is no one optimal size for a sample” — choice depen- ding on uses for the results and tolerable error, among other factors; (2) “There is no concise layman's proof of the absolute-numbers proposition”. —ED.) tichards — 30, 1980 - North Shote Néws - Don’t pester seal hunters Dear Editor: Mr. Speck’s recent spiel about the Greenpeace folk and the Newfie Seal hunters: these people have a tough enough life without being pestered by a bunch of goodies. Why, if they want to stop the killing of the seal pups, do they not get after the folk who buy the sealskin clothes. Just fancy them attempting to stop the sale of them in one of the big shops in New York, London, Parts, etc. , Incidentally has Mr. Speck, if he is not a vegetarian, ever enjoyed a meal of roast lamb? A.F. Menzies North Vancouver Bowte’s Fashions > Semi-Annual Clearance with fantastic reductions *x Koret Co-ordinates Values $23 to $32 Suits & Pantsuits Values $80 to $255 Sale Sweaters Values $16 to $65 Dresses Values $75 to $190 Sale Values $52 to $70 Values $80 to $100 - Values $120 to $145 Blouses Values $20 to $90... Long Gowns Values $44 to $200 Fur Coats & Jackets Values $1400 to $6500 $ Sale ew) vet Tralfons- 986 Park Royal South Use your Bowie's Courtesy Account Card — Bowte’s Makes Life Beautiful Williams Lake .. Sale 50% off | _. Sale 50% off $9999_$9999 39 99_§3Q 99 sate *29%° . Sale §29°° Sale 549°? Sale 50% off S99-54499