Selection bias in cluster trial
نویسندگان
چکیده
منابع مشابه
Reducing selection bias in a cluster randomized trial in West African villages.
Selection bias in cluster randomized trials may threaten the validity of the results. This bias may occur either at the level of the cluster or of the individual. We describe measures for maintaining comparability of intervention groups in a cluster randomized trial of a health education package to reduce dietary salt. The setting was 12 villages of the Ashanti region of Ghana. In total, 1896 v...
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data in Haneuse et al. [1] . The risk ratio of dementia by exposure in the total target population is 2.0, and is the true association (there is no confounding in our simple DAG; fig. 1 ). Table 1 shows the expected distribution by exposure and outcome by strata of dead/alive under the following assumptions: half of the population dies; there is a risk ratio of death for the exposed compared to...
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Language technology is biased toward English newswire. In POS tagging, we get 97–98 words right out of a 100 in English newswire, but results drop to about 8 out of 10 when running the same technology on Twitter data. In dependency parsing, we are able to identify the syntactic head of 9 out of 10 words in English newswire, but only 6–7 out of 10 in tweets. Replace references to Twitter with re...
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ژورنال
عنوان ژورنال: BMJ
سال: 2008
ISSN: 0959-8138,1756-1833
DOI: 10.1136/bmj.39514.402535.80