求翻译：选取青岛市职业病防治院2006年3月至2012年3月确诊的矽肺住院患者144例为调查对象，采用描述性流行病学方法进行统计分析。是什么意思？

Select the Qingdao Municipal Occupational Disease Prevention Hospital diagnosis of silicosis in March 2006 to March 2012, 144 cases of hospitalized patients for the survey, descriptive epidemiological methods for statistical analysis.

Qingdao City selected prevention and treatment of occupational diseases hospital in March 2006 to March 2012 diagnosed silicosis patients hospitalized for example 144 objects of the investigation, a description of statistical methods for epidemiological analysis.

Selects the Qingdao occupational disease to prevent and control the courtyard from March, 2006 the silicosis in hospital patient 144 examples which diagnoses to March, 2012 is the investigation object, uses the descriptive epidemiology method to carry on the statistical analysis.

Selected occupational diseases prevention and control in Qingdao between March 2006 and confirmed in 144 cases of inpatients with silicosis are the targets, using descriptive statistical analysis of epidemiological methods.

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