‘Meeste onderzoek levert foute conclusies op’
“Er is een toenemende zorg dat de meeste, of zelfs het overgrote gedeelte van hedendaags (medisch) onderzoek foute conclusies oplevert”.
Dat zegt de Griekse onderzoeker John Ioannidis in het internationale medische vakblad PLoS Medicine. Oorzaak van deze ‘false positives’ is het feit dat de meeste onderzoeken te kleinschalig zijn, de gemeten risicofactoren te klein zijn om te meten en de aanwezigheid van belangrijke financiële en politieke belangen en vooroordelen.
De man zegt zelfs dat hij in staat is om te bewijzen dat de meeste onderzoeken met onzinresultaten komen en hij laat dat ook zien in een simulatiemodel.
There is increasing concern that most current published research findings are false. The probability that a research claim is true may depend on study power and bias, the number of other studies on the same question, and, importantly, the ratio of true to no relationships among the relationships probed in each scientific field.
In this framework, a research finding is less likely to be true when the studies conducted in a field are smaller; when effect sizes are smaller; when there is a greater number and lesser preselection of tested relationships; where there is greater flexibility in designs, definitions, outcomes, and analytical modes; when there is greater financial and other interest and prejudice; and when more teams are involved in a scientific field in chase of statistical significance.
Simulations show that for most study designs and settings, it is more likely for a research claim to be false than true. Moreover, for many current scientific fields, claimed research findings may often be simply accurate measures of the prevailing bias.
Zijn bevindingen:
- The smaller the studies conducted in a scientific field, the less likely the research findings are to be true.
- The smaller the effect sizes in a scientific field, the less likely the research findings are to be true.
- The greater the number and the lesser the selection of tested relationships in a scientific field, the less likely the research findings are to be true.
- The greater the flexibility in designs, definitions, outcomes, and analytical modes in a scientific field, the less likely the research findings are to be true.
- The greater the financial and other interests and prejudices in a scientific field, the less likely the research findings are to be true.
- The hotter a scientific field (with more scientific teams involved), the less likely the research findings are to be true.
Als je al deze ‘regeltjes’ op anti-rokenonderzoek los laat blijft er weinig meer heel van de beweringen uit de anti-rokenhoek. Met name het vijfde punt scoort daar hoog: financiële en andere belangen zijn volop aanwezig.
