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May 23, 2002Stata Users Meeting, Maastricht1 Query your data with QD B. van der Holt / W.L.J. van Putten University Hospital Rotterdam - Daniel Department.

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Presentation on theme: "May 23, 2002Stata Users Meeting, Maastricht1 Query your data with QD B. van der Holt / W.L.J. van Putten University Hospital Rotterdam - Daniel Department."— Presentation transcript:

1 May 23, 2002Stata Users Meeting, Maastricht1 Query your data with QD B. van der Holt / W.L.J. van Putten University Hospital Rotterdam - Daniel Department of Trials & Statistics / HOVON Data Center

2 May 23, 2002Stata Users Meeting, Maastricht2 Introduction Correct data are crucial for any analysis; Ideally data should come cleaned and error free, but this is hardly ever the case. In clinical trial data may be distributed among several files. One way to check is to use if-expressions

3 May 23, 2002Stata Users Meeting, Maastricht3 Example Data from trial with over 400 patients –t1Randomisation/On study –t2PA form –t3Treatment form ** –t4Evaluation form ** –t5Off treatment form –t6Follow-up form ** –t7Infection form ** –t8Side effects form **

4 May 23, 2002Stata Users Meeting, Maastricht4 Checks for t1.dta

5 May 23, 2002Stata Users Meeting, Maastricht5 Checks for t3.dta

6 May 23, 2002Stata Users Meeting, Maastricht6 Disadvantage of if-expressions Errors in data of one patient may be found anywhere in the ouput: not neatly sorted by patient number. This will hamper easy admission of the data. (Remember that in this trial there were more than 400 patients)

7 May 23, 2002Stata Users Meeting, Maastricht7 Solution QD.ADO

8 May 23, 2002Stata Users Meeting, Maastricht8 QD (Query Data) Is a program by which one may query the quality and validity of data; Developed for clinical trials, but not restricted to it; Define a series of tests on the data in dta- files; The data may be in one ore more dta-files, linked by a common index variable (a unique case-identifier);

9 May 23, 2002Stata Users Meeting, Maastricht9 QD (Query Data) - continued Generates formatted reports of variable- values with messages associated with the test; And, very important: the reports are organised by case (e.g. patient), and not listwise by test! All tests that are true for a single case are displayed together.

10 May 23, 2002Stata Users Meeting, Maastricht10 QD output for patient 2

11 May 23, 2002Stata Users Meeting, Maastricht11 QD output for patient 5

12 May 23, 2002Stata Users Meeting, Maastricht12 Syntax of QD.ADO The general syntax of the program is: qd options The commands that were used to generate the previous output will be used for illustration

13 May 23, 2002Stata Users Meeting, Maastricht13 * QDCHECK.DO - 1 qd clear –removes all previously defined QD parameters (global macros) from memory qd files(t1 t2 t3) –required. Contains the (valid) names of one or more dta-files. The same dta-file may appear more than once. The files are numbered by QD in the natural order of appearance in the string as file 1, file 2,...

14 May 23, 2002Stata Users Meeting, Maastricht14 * QDCHECK.DO - 2 qd by(hvnr) –required. Defines an ordering on file 1 and variable by which the records in the different files are linked qd title(HOVON xx NHL Checks on data) –This title will be printed on top of the output of the data of each case

15 May 23, 2002Stata Users Meeting, Maastricht15 * QDCHECK.DO - 3

16 May 23, 2002Stata Users Meeting, Maastricht16 * QDCHECK.DO - 4

17 May 23, 2002Stata Users Meeting, Maastricht17 * QDCHECK.DO - 5 qd log(qdcheck.log) –defines the name (path) of the file that will serve as a log file to which the output will be written. When not defined, the output will only be shown on the screen qd print(if hvnr<=5) –this is the instruction to display the results of all the tests on the screen and, if defined, to a log-file.

18 May 23, 2002Stata Users Meeting, Maastricht18 Further information findit qd email: holt@stah.azr.nl


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