Missing self-report data due to inability or unwillingness to provide information
Missing data in medical records or patients' personal records
Conflicting data provided by different sources (patient vs. caregiver) or at different times
Different information given by participants to nurses versus physicians versus researchers
Different, sometimes conflicting data provided to different research personnel, depending on participant-researcher relationship, race or sex differences
Difficulty determining the reason for contradictory information in real-time
Difficulty capturing certain contextual data in real-time, such as gestures, tone, smell
Potential for biased sampling when clinicians recommend or select patients for participations
Participants have hard time remembering events in question or speaking about the research topic, but researchers are not aware of this
Analyzing large volumes of qualitative and mixed data to assess data quality and validity in real- time is time consuming
Difficulty interpreting whether participants' experience and perceptions align with the group to which they were assigned (e.g., diagnosis category, intervention vs. control condition)