Margin of error - Wikipedia, the free encyclopediaHowever, the margin of error only accounts for random sampling error, so it is blind to systematic errors that may be introduced by non-response or by interactions between the survey and subjects' memory, motivation, communication and knowledge.
Margin of error - Wikipedia, the free encyclopediaIf the exact confidence intervals are used, then the margin of error takes into account both sampling error and non-sampling error. If an approximate confidence interval is used (for example, by assuming the distribution is normal and then modeling the confidence interval accordingly), then the margin of error may only take random sampling error into account. It does not represent other potential sources of error or bias such as a non-representative sample-design, poorly phrased questions, people lying or refusing to respond, the exclusion of people who could not be contacted, or miscounts and miscalculations.
Margin of error - Wikipedia, the free encyclopediaFor a simple random sample from a large population, the maximum margin of error is a simple re-expression of the sample size n. The numerators of these equations are rounded to two decimal places.
Margin of error at 99% confidence \approx 1.29/\sqrt{n}\,
Margin of error at 95% confidence \approx 0.98/\sqrt{n}\,
Margin of error at 90% confidence \approx 0.82/\sqrt{n}\,
If an article about a poll does not report the margin of error, but does state that a simple random sample of a certain size was used, the margin of error can be calculated for a desired degree of confidence using one of the above formulae. Also, if the 95% margin of error is given, one can find the 99% margin of error by increasing the reported margin of error by about 30%.
Why are we Afraid to Tax the Super-Rich « SpeakEasyIn theory this sounds good. But we tried this experiment, and it didn’t work. When we cut taxes on the super-rich, we got a different kind of investment boom than the politicians and economists had promised. The wealthy literally ran out of investments in factories, equipment and even services. So they flocked to financial investments — which were supposedly safer and more profitable anyway. The super-rich laid their money down in the Wall Street casino, and helped puff up bubble after bubble. Profits in the financial sector soared. In 1960, the sector accounted for about 15 per cent of all corporate profits. By 2008 (before the crash, that is), it was almost 40 percent. The financial sector crased as the direct result of tax cuts for the super-rich and Wall Street deregulation.
Working for Cents on the Dollar: Race and Ethnic Wage Gaps in the Noncollege Labor MarketThis paper uses data from the 2007 Survey of Employers in the Low-Skill Labor Market to analyze whether wage differences among workers of different races and ethnicities in the low-skill labor market remain after controlling for individual, job, and employer characteristics. The employer-provided data include detailed information on job requirements and employer characteristics rarely available in household surveys. We find that black workers earn significantly less than white workers in the less-skilled labor market, and a significant difference (12 percent) remains even after controlling for worker, job, and employer characteristics.
The Ugly Truth About Beauty - ABC NewsWomen will take just about any shortcoming in a man, except in the height department, according to Andrea McGinty, who founded the San Diego-based dating service It's Just Lunch.
McGinty helped ABCNEWS put together an experiment to test just how willing women are to date shorter men. We brought together several short men and asked them to stand next to taller men. We invited groups of women to look at the men and choose a date.
To see if the women would go for short guys who were successful, ABCNEWS' Lynn Sherr created extraordinary résumés for the shorter men. She told the women that the shorter men included a doctor, a best-selling author, a champion skier, a venture capitalist who'd made millions by the age of 25.
Nothing worked. The women always chose the tall men. Sherr asked whether there'd be anything she could say that would make the shortest of the men, who was 5 feet, irresistible. One of the women replied, "Maybe the only thing you could say is that the other four are murderers." Another backed her up, saying that had the taller men had a criminal record she might have been swayed to choose a shorter man. Another said she'd have considered the shorter men, if the taller men had been described as "child molesters."
Building a Better Teacher - NYTimes.comBut what makes a good teacher? There have been many quests for the one essential trait, and they have all come up empty-handed. Among the factors that do not predict whether a teacher will succeed: a graduate-school degree, a high score on the SAT, an extroverted personality, politeness, confidence, warmth, enthusiasm and having passed the teacher-certification exam on the first try. When Bill Gates announced recently that his foundation was investing millions in a project to improve teaching quality in the United States, he added a rueful caveat. “Unfortunately, it seems the field doesn’t have a clear view of what characterizes good teaching,” Gates said. “I’m personally very curious.”
Building a Better Teacher - NYTimes.comWilliam Sanders, a statistician studying Tennessee teachers with a colleague, found that a student with a weak teacher for three straight years would score, on average, 50 percentile points behind a similar student with a strong teacher for those years. Teachers working in the same building, teaching the same grade, produced very different outcomes. And the gaps were huge. Eric Hanushek, a Stanford economist, found that while the top 5 percent of teachers were able to impart a year and a half’s worth of learning to students in one school year, as judged by standardized tests, the weakest 5 percent advanced their students only half a year of material each year.
Smartphones have changed the way we travel - USATODAY.com"My iPhone has changed my life," says Al Diamond, an insurance industry consultant from Cherry Hill, N.J. Besides using the phone as an airline boarding pass and GPS, Diamond uses the Expense Tracker app to keep tabs on expenses, TripIt to organize itineraries, Inrix Traffic to avoid running into congestion on the road and Free Wi-Fi to find hot spots.
Couples study debunks 'trial marriage' notion of cohabiting - USATODAY.comCohabitation has increased so rapidly that the data about it haven't kept pace with the growing numbers, researchers say. The latest U.S. Census for 2008 reported 13.6 million unmarried, heterosexual couples living together. Researchers say 50% to 60% of couples who marry today lived together first; some note that 70% of young adults will cohabit. Most couples who live together either marry or break up within two years.
No Supreme Court hearing for mom who asked to read Bible to son's class / The Christian Science Monitor - CSMonitor.comChief Judge Anthony Sirica in a 2-to-1 decision handed down in June by the Third US Circuit Court of Appeals. “But a reading from the Bible or other religious text is more than a message and unquestionably conveys a strong sense of spiritual and moral authority,” he wrote. “In this case, the audience is involuntary and very young. Parents of public school kindergarten students may reasonably expect their children will not become captive audiences to an adult’s reading of religious texts.”
Damn Interesting • The Ethyl-Poisoned EarthA study published in the peer-reviewed journal Environmental Research, which used data spanning more than fifty years, reported a “very strong association” between the exposure of young children to lead, and crime rates twenty years later when they became young adults. This correlation holds true for a wide variety of locales, social conditions, and models of government.
Lead exposure, crime seem to correlate - USATODAY.comHe found a "stunning" fit, he says. The trend lines match almost perfectly: Leaded-gas use climbed in the 1940s and fell in the early 1970s; 23 years later, rates for violent crime followed in near unison. He also studied lead-paint levels from 1879 over the next 60 years, matching them to murder rates from 1900 to 1959.
Overweight Older People Live LongerLast summer, researchers in Canada reported the same findings after analyzing data from more than 11,000 adults followed for more than a decade.
In that study, people who met the criteria for being overweight were 17% less likely to die compared to people of normal weight.
In the newly reported research, overweight study participants in their 70s followed for up to 10 years had a 13% lower risk of death than participants classified as normal weight.
Daily Kos :: State of the NationQUESTION: Would you favor or oppose giving illegal immigrants now living in the United States the right to live here legally if they pay a fine and learn English?
Abstinence-only classes may be effective for young teens - latimes.comOver the two years after taking the classes, 48.5% of those in the control group reported sexual activity, compared with 33.5% of those in the abstinence-only group. About 52% of those taught only safe sex reported sexual activity, and about 42% of those in the comprehensive class made a similar report.
