Analysis Across Tests: Dunnett's Analysis For Shelf-life Testing Data

Analysis Across Tests: Dunnett's Analysis For Shelf-life Testing Data

Overview 

The recommended analysis for shelf-life testing data is the Dunnett's test. Dunnett's test compares a (blind) control against each test sample.

This workflow will help you select specific analysis options when generating the PowerPoint Report in the Advanced search & analysis across tests area to ensure proper Dunnett's analysis on your shelf-life data that is not linked to products. The same steps can be applied to other report types, such as Summary Report, Top Box Report, and raw data export.



Before You Begin 

  1. Please be sure to follow the test setup workflow for shelf-life testing that best suites your testing needs.

  2. This analysis workflow is applicable to real-time shelf-life time point testing data and accelerated shelf-life testing data collected in multiple tests.

  3. For analysis purposes it is very important that the Sample type  of your time point 0 (first test's) control sample is set to Control. The steps below can be performed even after data is collected, in case it was not done before data collection. 
  1. If you already set your test to Complete, undo complete to be able to follow the remaining steps.

  2. In the  Samples & design  tab of your time point 0 test, click Edit samples.

  3. Locate the sample you wish to mark as a Control

  4. Click on the   Sample type   dropdown list for that sample and select  Control  .  


  5. Click Save to save the changes.

Only one sample should be set as a Control sample type for Dunnett's analysis to run successfully.



Search For Your Shelf-life Tests

  1. On the Dashboard, click Advanced search & analysis across tests.

  2. Use the different criteria available to find all the tests you wish to include in your analysis.

  3. Select the tests you wish to run the analysis on. If you wish to easily select them all, click in the first checkbox, the one in the heading row.
    Maximum number of samples the Dunnett's test can run on is 17. If you have more than 17 samples, run the report two times. Either at this stage deselect some test, or if unsure how many samples each test has, select all tests and then filter out some of the samples when you go to generate the reports. By doing this you will still get the proper analysis because Dunnett's test compares each individual sample to the (blind) control.


  4. Click Reports to open the Analysis across tests page. Follow the next set of steps to generate the report.



Generate The PowerPoint Report

  1. If you would like to filter your data, in the top right-hand corner click Filters and use one, some, or all of the below filtering options:
    1. Sample sets. You can filter out sample sets for individual tests selected in the list.


    2. Samples. Samples from all tests are displayed in the tab. The test name they belong to will be displayed in the screen. Filter samples out as necessary.

      Maximum number of samples the Dunnett's test can run on is 17. If you have more than 17 samples, run the report two times filtering out some of the samples, making sure to include the control sample in both reports. By doing this you will still get the proper analysis because Dunnett's test compares each individual sample to the (blind) control.

    3. Reps. If any of the tests had reps defined in them, you will be able to filter reps out.


  2. Under the Report type, select PowerPoint report .

    This is where you can select a different report type if you wish to do so. Please be sure to review all the options for different reports to select what meets your analysis needs.

  3. Under the Options, make the following selections:  
    1. Under the Sample grouping options, select Treat each sample as unique. This will ensure that even if you accidentally forgot to update the sample name for one of the time points that the analysis will treat them as unique rather than group data for samples with the same name, for example.


      For report clarity you might want to ensure that the sample names are correct before running the reports. You can update sample names even when data is collected, but the test cannot be set to Complete. If you already set it to Complete and need to make changes in sample names, undo complete, make the change, set the test back to Complete and run the analysis.

    2. Review the Report format and details options and make selections as needed.

    3. Under the Analysis options from defaults, click Change advanced analysis options

    4. Select Dunnett's test  at the significance level of your choice and save the changes. ANOVA model used in all analysis across tests is 1-way ANOVA.

  4. Under the Questions, click Choose questions, review and select the questions you wish to include in the analysis.

  5. Under the Export, the only option available for the PowerPoint Report is .pptx. Other report types will have different options to choose from.

  6. Update the name for your report and click Create my report. Download and review the report.

Maximum number of samples the Dunnett's test can run on is 17. If you have more than 17 samples, run the report two times filtering out some of the samples, making sure to include the control sample in both reports. By doing this you will still get the proper analysis because Dunnett's test compares each individual sample to the (blind) control.


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