In every research there are always potential threats to validity and in the reviewed article Boffetta et al, there are several like; confounding, situation, and single group threats among others. Before we proceed with the explanation of the above identified threats to validity, perhaps it is important to first understand what validity is with respect to research methods and its key components. Validity is the greatest estimate of the certainty in conclusion or inferences, generally of cause and effect.1 One of the key features of determining cause and effect that Boffetta et al does not meet is the No Plausible Alternative Explanation, which is the fact that no other causes can lead to the hypothesized effect.1 In summary, the article Boffetta et al performed and evaluated of data from the study by the European Prospective Investigation into Cancer and Nutrition (EPIC)1992-2000. The goal was see if relationships between high intake of total fruits and vegetables and cancer risk existed.2 Boffetta et al, concluded that high fruits and vegetable intake was beneficial to cancer prevention. Also that there was no substantial evidence of high fruits and vegetables are linked to cancer risks as may be portrayed.
The No Plausible Alternative Explanation described earlier was a major issue in the Boffetta et al, in that even though they addressed other causes of cancer i.e. smoking, alcohol, they did not address others like the mutations and predispositions. Some people have a genetic predisposition to cancer if they carry certain genes like BRCA1 and BRCA2.3
The validity threat of confounding was evident in the Boffetta et al. They did not address other variables like physical activity that the subjects could have incorporated in their lives, which in turn may have been a major factor in preventing cancer rather than high Fruits and vegetable intake. Studies show that increased physical activity is key in preventing cancers specifically colon, prostate, and breast cancer.4 In fact in the conclusion Boffetta et al acknowledges “we cannot entirely rule out the possibility of residual confounding by these or other factors”.
Single group was another threat to validity that was evident in Boffetta et al. The data for their base line group was only based on answers of the subjects from their past one year history of not eating or eating fruits and vegetables, while the experimental group was observed for 8.7 years. A control group is vital to evaluate the baseline or effects without the program, treatment,1 and in this case a group that did not eat high fruits and vegetables should have been observed also for 8.7 years.
Situation was yet another threat to validity in Boffetta et al, in that the timing/time, conditions, location, type of fruits and vegetables, and age may have been other influencing factors in the results. The data was based on subjects that were observed for 8.7 years, which is a very long time since subjects grow up, go...