W2 - OS Measurement Precision Study (OS-MPS)

This page provides study documentation for Core Study W2.  For description of the specimen results, see Specimen Results Description (open to public). Data sets of the specimen results are included in the existing WHI datasets located on the WHI Data on this site (sign in and a completed Data Distribution Agreement are required; see details on the Data site).

Investigator Names and Contact Information

Core study approved by WHI Steering Committee.


The OS Measurement Precision Study (OS-MPS) included a subsample of 1,000 women randomly selected from among new OS enrollees between September 1, 1996, and May 30, 1997. Twenty-five women were randomly chosen at each of the 40 clinical sites to participate in this study.  The selection was stratified by both ethnicity and age. The participants were asked to repeat four of the questionnaires from the baseline CC visit approximately 10 weeks after OS enrollment, and to return to the CC to have their blood drawn.  The OS-MPS provided data about the reproducibility of measures such as physical activity and reproductive history from the self-administered questionnaires, and repeat fasting blood samples to test the accuracy of future blood measures.
The subset of questionnaires that each participant was separated into two groups:
The following lists specify the questionnaires and procedures that will be completed by the OS-MPS participants at the CCs assigned to Group A or Group B:
Group A:
Group B:
Form 2 - Eligibility Screen (selected questions)
Form 20 - Personal Information (selected questions)
Form 30 - Medical History Questionnaire
Form 31 - Reproductive History Questionnaire
Form 37 - Thoughts and Feelings
Form 32 - Family History Questionnaire
Form 42 - Observational Study Questionnaire
Form 34 - Personal Habits Questionnaire
Form 100 - Blood Collection and Processing
(completed by clinic staff)
Form 100 - Blood Collection and Processing
(completed by clinic staff)
For more details, see the description of study, including timeline and data collected, in the WHI Manual, Vol. 2, Section 8.4 – OS Measurement Precision Study – OS-MP.
Assay methodologies can be found here.
See publications: 442, 524.  WHI publications by study lists published WHI papers that have been generated by ancillary studies. A complete list of WHI papers is available in the Bibliography section of this website.
 For a summary of the blood results, see
  • Aug 1999 Semi-Annual Progress Report
    - Section 5.3:  Laboratory Analysis – OS
    - Table 5.2 – Blood Specimen Analysis:  OS-MPS Participants