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A sneak peek into the NSRR standardized metadata for validated survey instruments

Any researchers who have tried to combine multiple datasets or validate findings in another dataset know how heterogeneity across datasets can make the process difficult or even impossible. At NSRR, we are working to address these challenges by standardizing and harmonizing important sleep measures and non-sleep covariates retrospectively. Standardization aims to reach uniformity in metadata across datasets, be it channel labels, annotations, variable definitions, sleep terminology, etc. Retrospective harmonization, on the other hand, aims to improve comparability of the same latent construct represented differently in different datasets, which usually require subject matter knowledge to assess the heterogeneity and to make decisions to generate inferentially equivalent (harmonized) content across datasets. As discussed in Dr. Mazzotti’s blog post, the Sleep Research Society (SRS) has recognized the importance of supporting harmonization of sleep and circadian data. The NSRR has developed various strategies for metadata standardization and data harmonization to address unique challenges in each domain (i.e., non-sleep covariates, sleep questionnaires, polysomnography summary and signal data, actigraphy data, etc.) Here, we showcase one of the approaches we developed.

As part of the data and metadata harmonization effort at NSRR, we have standardized selected survey instruments and developed a tagging system that can be used to search and to browse either aggregate scores or specific questions from a given instrument, within and across datasets. Our initial priorities were selected sleep standardized questionnaires.

Here we highlight the harmonization of information collected using the Epworth Sleepiness Scale. Previously, users needed to try different keywords to find ESS questions – such as, “epworth”, “ess”, “dozing”, etc., because none of these keywords were consistently used in variable labeling across datasets. Now that the folder structure has been standardized for all datasets, ESS variables are always located in “Sleep Questionnaires/Hypersomnia”. Alternatively, users can use standardized keywords (i.e., tags) to search for aggregate scores or individual questions.

To search for ESS variables within a dataset

  1. Click the link for the dataset
  2. Click the Variables tab
  3. Click the search icon
  4. Enter ‘ess' or ‘epworth’ in the search field (not case sensitive)
  5. Click on the retrieved variable name
    • Tagged variables include a ‘Search for all ESS variables in this dataset’ link that can be clicked to retrieve the full set of ESS variables
    • Sidebar links listed under the Graphs heading can be clicked to retrieve graphic and tabular breakdowns of baseline results categorized by Treatment Arm, Age, Gender, and Race


To search for ESS variables across datasets

  • Option 1
    1. Click the search icon in the site navigation bar
    2. The following tags will return corresponding variables from all datasets
      • ess_total - Total score of Epworth Sleepiness Scale (ESS)
      • ess_1sitread - Chance of dozing while sitting and reading
      • ess_2watchingtv - Chance of dozing while watching TV
      • ess_3sitinactive - Chance of dozing while sitting, inactive in a public place
      • ess_4passenger - Chance of dozing as a passenger in a car for an hour without a break
      • ess_5lyingdown - Chance of dozing while lying down in the afternoon when circumstances permit
      • ess_6sittalk - Chance of dozing while sitting and talking to someone
      • ess_7afterlunch - Chance of dozing while sitting quietly after lunch without alcohol
      • ess_8stoppedcar - Chance of dozing while in a car, while stopped for a few minutes in traffic
      • epworth – all ess variables including the total score
  • Option 2
    1. Navigate to the Epworth Sleepiness Scale variables of interest (e.g. ess_1sitread) in any dataset
    2. Click on the ess_1sitread tag
    3. ess_1sitread variable from all datasets will be shown in the search results


Users can use the following tags to explore other standardized survey instruments:

  • whiirs - Women's Health Initiative Insomnia Rating Scale (WHIIRS)
  • mossf36 - Medical Outcomes Study Short Form 36 (SF-36)
  • phq9 - Patient Health Questionnaire 9 (PHQ-9)
  • homeq - Horne-Ostberg Morningness-Eveningness Questionnaire
  • fosq - Functional Outcomes of Sleep Questionnaire
  • isi - Insomnia Severity Index (ISI)


    In addition to validated sleep survey instruments, we’ve also started standardizing and harmonizing a wide range of demographic, lifestyle, and clinical and polysomnography data (to be introduced in future blog posts).

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    By yzhang on November 8, 2022 Nov 8, 2022 in Releases
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