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--- wiki:guide:research:extract [2022/05/10 21:03]
tiffany [Extract Data Elements]
+++ wiki:guide:research:extract [2022/05/17 02:17]
tiffany old revision restored (2022/05/10 21:25)
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-==== A note about Continuous Variables ====
+===== A note about Continuous Variables =====
-Once the variables to be collected are defined, the way in which continuous variables will be extracted needs to be determined. This can be done by choosing a central tendency measure (mean or median) and a dispersion measure (standard deviation, median, or range).
+The way in which continuous variables will be extracted needs to be determined. This can be done by choosing a central tendency measure (mean or median) and a dispersion measure (standard deviation, median, or range).
 There are four options that are typically reported: <font 10.5pt/Arial,Helvetica,sans-serif;;#333333;;white>mean (SD),</font> <font 10.5pt/inherit;;#333333;;white>mean (range),</font> <font 10.5pt/inherit;;#333333;;white>median (range),</font> <font 10.5pt/inherit;;#333333;;white>median (IQR).</font>
-  * <font 10.5pt/Arial,Helvetica,sans-serif;;inherit;;white>The mean/median or the SD/range/IQR may not be present in all studies included for extraction. If this is the case, leave blank/empty. It is not recommended that a mean is entered in place of a median or vice versa.</font>
+  * <font 10.5pt/Arial,Helvetica,sans-serif;;inherit;;white>The mean/median or the SD/range/IQR may not be present in all studies included for extraction. If this is the case, leave blank/empty. Do not enter the mean as the median or vice versa.</font>
   * <font 10.5pt/Arial,Helvetica,sans-serif;;inherit;;white>Standard Error Versus Standard Deviation - a</font> <font 10.5pt/inherit;;inherit;;white>common mistake in the extraction of continuous outcome data is the use of the standard error instead of the standard deviation (Harris et al., 2019). The standard deviation can be obtained by multiplying the standard error of the mean by the square root of the sample size.</font>
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-===== Extract Data Elements =====
-  - <font 10.5pt/Arial,Helvetica,sans-serif;;#333333;;white>**Select Intervention Arms** and extract the number of participants in each group</font>
+===== Check Reported Outcomes Carefully =====
-  - <font 10.5pt/Arial,Helvetica,sans-serif;;#333333;;white>**Extract time point data** (when the outcomes were assessed). For example, time point for baseline would be zero days and time point for the outcome would be 28 days. If there are multiple time points choose the time point that is used for the primary outcome.</font>
+  * Check units of data elements to ensure that they are reported in a consistent way. Make sure that elements are being extracted at the same time point (for instance, 7-day versus 28-day mortality) and that the wording of the study is consistent with what is being collected.
-  - ** <font 10.5pt/Arial,Helvetica,sans-serif;;#333333;;white>Extract data elements</font>   **
+  * Papers will sometimes report outcomes in ways that are close but not exactly the same. For instance, while the majority of studies may report cardiovascular disease, other studies may report coronary artery disease. Because coronary artery disease is a type of coronary heart disease, it would typically be fine to extract coronary artery disease into a data element called cardiovascular disease.
-  * <font 10.5pt/Arial,Helvetica,sans-serif;;#333333;;white>__Check units of data elements__</font> <font 10.5pt/inherit;;#333333;;white>to ensure that they are reported in a consistent way. Make sure that elements are being extracted at the same time point and that the wording of the study is consistent with what is being collected. For instance, 28-day mortality is different from 7-day mortality.</font>    <font 10.5pt/inherit;;#333333;;white>In general, there is more flexibility with patient characteristics rather than with the outcomes. Papers will sometimes report outcomes in ways that are close but not exactly the same. For instance, while the majority of studies may report cardiovascular disease, other studies may report coronary artery disease. Because coronary artery disease is a type of coronary heart disease, it would typically be fine to extract coronary artery disease into a data element called cardiovascular disease.</font>
-  * <font 10.5pt/Arial,Helvetica,sans-serif;;#333333;;white>__Appropriate populations__</font> <font 10.5pt/inherit;;#333333;;white>- A major issue in meta-analysis involves clinical or methodological heterogeneity among the combined studies. In the case of large heterogeneity, the estimate of the overall effect will be of questionable value (Kontopantelis and Reeves, 2009).</font>
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-=====   =====
-====== Best Practices for Data Extraction: NK Software ======
+===== Best Practices for Data Extraction: NK Software =====
-[[:wiki:autolit:extraction|Please refer to the AutoLit section that reviews the steps for data extraction]].
+[[:wiki:autolit:extraction|How to perform data extraction in Nested Knowledge]].
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