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. Author manuscript; available in PMC: 2012 Sep 18.
Published in final edited form as: Cancer Biomark. 2010;9(1-6):531–549. doi: 10.3233/CBM-2011-0183

Table 1.

Examples of potential sources of bias in tissue sets

  1. Systematic differences among the sites of sample collection

  2. Population (e.g., racial mixtures, differences in sex and age, ethnicity)

  3. Diurnal variations (i.e., time of collection)

  4. Homeostasis (e.g., fed or fasting state)

  5. Stress of donors

  6. Comorbidity (diabetics versus hypertensive patients)

  7. Collection container (red top vs. tiger separator or type of plasma)

  8. Time from processing to freezing

  9. Temperature and length of storage

  10. Freeze thaw cycles