Researchers wants to investigate whether previous Helicobacter pylori infection is linked to gastric cancer. They recruit patients who already have gastric cancer and compare them with individuals without gastric cancer, They then review past medical records to determine previous Helicobacter pylori infection status. Which study design does this describe? 单项选择题
A
Cross-sectional study
B
Case-control study
C
Prospective cohort study
D
Non-randomized trial
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A research team wanted to look at the different factors that are associated with type 2 diabetes. They recruited 100 participants with type 2 diabetes and 250 participants without type 2 diabetes and then administered a questionnaire to all participants to assess their risk factors including their age, gender, diet, sedentary behaviour, smoking status and drinking status. This study is an example of a:
These data come from a case-controlled study to examine the potential relationship between age at first pregnancy and cervical cancer. In a case-control study a random sample of cases (i.e. people with the disease in question) and controls (i.e. people similar to those in the case group, except they do not have the disease) and the proportion of people with some potential risk factor are compared across the two groups. In this study we will be comparing the proportion of women who had their first pregnancy at or before the ages of 25, because researchers suspected that an early age at first pregnancy leads to increased risk of developing cervical cancer. The data is presented in the table below: Age at First Pregnancy <=25 Age at First Pregnancy>25 Cervical Cancer 42 7 Control 203 114 Were the conditions for this test met?
These data come from a case-controlled study to examine the potential relationship between age at first pregnancy and cervical cancer. In a case-control study a random sample of cases (i.e. people with the disease in question) and controls (i.e. people similar to those in the case group, except they do not have the disease) and the proportion of people with some potential risk factor are compared across the two groups. In this study we will be comparing the proportion of women who had their first pregnancy at or before the ages of 25, because researchers suspected that an early age at first pregnancy leads to increased risk of developing cervical cancer. The data is presented in the table below: Age at First Pregnancy <=25 Age at First Pregnancy>25 Cervical Cancer 42 7 Control 203 114 What is the conclusion for this test?
These data come from a case-controlled study to examine the potential relationship between age at first pregnancy and cervical cancer. In a case-control study a random sample of cases (i.e. people with the disease in question) and controls (i.e. people similar to those in the case group, except they do not have the disease) and the proportion of people with some potential risk factor are compared across the two groups. In this study we will be comparing the proportion of women who had their first pregnancy at or before the ages of 25, because researchers suspected that an early age at first pregnancy leads to increased risk of developing cervical cancer. The data is presented in the table below: Age at First Pregnancy <=25 Age at First Pregnancy>25 Cervical Cancer 42 7 Control 203 114 What is the appropriate null hypothesis to determine if there is an association between age at first pregnancy and later development of cervical cancer?
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