Every year hundreds of science papers are retracted, most involving no blatant malfeasance, but others are due to cooked data. And 2011 was no different.

Bad science papers can have lasting effects. Consider the 1998 paper in the journal the Lancet that linked autism to the MMR vaccine for measles, mumps and rubella. That paper was fully retracted in 2010 upon evidence that senior author Andrew Wakefield had manipulated data and breached several proper ethical codes of conduct.

Nevertheless the erroneous paper continues to undermine public confidence in vaccines. After the Lancet article, MMR vaccination rates dipped sharply and haven't fully rebounded. This decline in the MMR vaccine has been tied to a rise in measles cases resulting in permanent injury and death.

Each year hundreds of peer-reviewed scientific articles are retracted. Most involve no blatant malfeasance; the authors themselves often detect errors and retract the paper. Some retractions, however, as documented on the blog Retraction Watch, entail plagiarism, false authorship or cooked data.

No journal is safe from retractions, from the mighty "single-word-title" journals such as Nature, Science and Cell, to the myriad minor, esoteric ones.

Yet as astronomer Carl Sagan once said, "Extraordinary claims require extraordinary evidence." Below are five science results retracted in 2011, pulled permanently off the books in part for falling far short of meeting the Sagan standard.

#5: Los Angeles marijuana dispensaries lead to drop in crime.

Keep smoking. The RAND Corporation retracted its own report in October after realizing its sloppy data collection.

Crime data compiled from neighborhoods with these highly contentious medical marijuana dispensaries supposedly revealed slightly lower crime rates. The authors attributed this decline not to marijuana itself but rather the presence of security cameras and guards in and around the dispensaries, having a positive effect on the neighborhood. [The History of 8 Hallucinogens]

The L.A. city attorney's office was incensed with the report, having argued the opposite — that the dispensaries breed crime. The city's lawyers soon found critical flaws in RAND's data collection, largely stemming from RAND's reliance on data from CrimeReports.com, which did not include data from the L.A. Police Department. RAND blamed itself for the error, not CrimeReports.com, which had made no claims of having a complete set of data, and, in fact, didn't even know about the study.

#4 -- Butterfly meets worm, falls in love, and has caterpillars.

The Proceedings of the National Academy of Sciences (PNAS) published a fantastic claim in 2009 by zoologist Donald Williamson, which was delightfully reported in the science news media. Williamson claimed that ancestors of modern butterflies mistakenly fertilized their eggs with sperm from velvet worms. The result was the necessity for the caterpillar stage of the butterfly life cycle.

The PNAS paper got a few laughs among evolutionary scientists, but it hasn't yet been retracted. Williamson's follow-up 2011 paper in the journal Symbiosis, however, has been retracted.

Researchers Michael Hart and Richard Grosberg at the University of Texas, Austin, systematically refuted all of Williamson's claims in the pages of PNAS by the end of 2009. They based their arguments entirely on well-known concepts of both basic evolution and the genetics of modern worms and butterflies. When Symbiosis published its butterfly-meets-worm article in January 2011, Hart raised questions with the editor. As of November the paper is no longer available.

#3: Treat appendicitis with antibiotics, not surgery.

The Journal of Gastrointestinal Surgery published an article in 2009 by Indian researchers titled "Conservative management of acute appendicitis." The gist was that antibiotics might be a safe alternative to an appendectomy, the surgical removal of the appendix.

Well, maybe not. The journal retracted the paper in October. Italian surgeons had raised a red flag with the study in a lengthy letter published in 2010 in the same journal, politely citing a multitude of problems with the study's methodology. The Indian researchers responded a month later with their own two-paragraph letter defending the methodology and calling for a larger study to establish the superiority of antibiotic treatment over surgery.

There's no word whether that larger study is pending, but the journal's editors retracted the original article for reasons of alleged plagiarism, stating that "significant portions of the article were published earlier" by other researchers in 2000 and 1995.

#2: Litter breeds crime and discrimination.

It sounded so reasonable: Graffiti and litter in urban settings can trigger changes in the brain that can lead to crime, hatred and discrimination. Alas, the senior author of this April 2011 paper in Science, Dutch social psychologist Diederik Stapel, might have fabricated much of the data.

The journal Science retracted the paper in November upon realization that Stapel, a media darling whose name frequented the New York Times, may have faked data in at least 30 papers, according to a report from Stapel's university, Tilburg University in the Netherlands. Stapel has since been suspended from Tilburg pending further investigation.

The objective reader must now question other pet theories from Stapel. These include his "findings" that beauty-advertising works because it makes women feel worse about themselves, and that conservative politics leads to hypocrisy.

#1: Chronic fatigue syndrome is caused by a virus.

Chronic fatigue syndrome (CFS) is a disorder of unknown origin. Some researchers, in fact, consider this a psychological disorder largely confined to wealthier countries, affecting women more than men.

Then came a study published in Science in October 2009 by researchers from the Whittemore Peterson Institute in Reno, Nevada. The researchers associated CFS with something called xenotropic murine leukemia virus-related virus (XMRV), which they said they found in blood samples of patients with CFS.

CFS advocates were elated. At last there was proof that their disease was real, they said. Retrovirus experts, on the other hand, were skeptical. Maybe the blood samples were contaminated. It turns out that the paper is likely wrong. No other lab could reproduce the results.

Science issued an "Editorial Expression of Concern" in July after the authors themselves refused to retract their paper. The Science editorial states bluntly that the study purported "to show that … XMRV was present in the blood of 67 percent of patients with chronic fatigue syndrome compared with 3.7 percent of healthy controls. Since then, at least 10 studies conducted by other investigators and published elsewhere have reported a failure to detect XMRV in independent populations of CFS patients."

The authors finally issued a partial retraction in September, removing data now known to be from contaminated samples. Science followed with a full retraction on Dec. 23. Meanwhile, in a disturbing twist, senior author Judy Mikovits was fired from the Whittemore Peterson Institute in September and arrested in California in November over charges for possession of stolen property and unlawful taking of computer data, equipment and supplies. Science is investigating whether the data were manipulated.

Following the history of this paper is enough to make you fatigued.

Christopher Wanjek is the author of the books "Bad Medicine" and "Food At Work." His column, Bad Medicine, appears regularly on Live Science.