Measuring and building models of behavior

Monique HendriksPhilips Research, Eindhoven

David A. AschUniversity of Pennsylvania

US Department of Veterans Affairs

Fundamental goals of models of behavior

The reason to develop models of behavior is to understand how to change behavior in order to improve outcomes.

Keeping this goal in sight provides priority to our efforts.» We should give more attention to determinants of

behavior change.» We should give more attention to determinants of

behavior change that seem feasible.» We should give more attention to determinants of

behavior change that seem feasible and relevant to outcomes we care about.

Behavior change in real life is what is important

Behavior change in real life is likely to be different from behavior change in laboratory settings.

In laboratory settings, participants have to provide consent and must agree to all sorts of unusual regulatory and monitoring activities.

Although randomized trials provide excellent internal validity, these consent processes and the often artificial settings substantially reduce external validity or generalizability.

Threats to behavior change that arise from real world issues may not arise in laboratory settings.

Internal validity competes with external validity

Trials limit generalizability because they select on:» The motivation to participate in an experiment» The willingness to tolerate intrusive monitoring» The artificialness of short time-defined trial

Each of these selects for more motivated participants and also provides these participants with a time limited exposure.

These challenges are more important in behavior change research than in drug trials.

Adherence to drug therapy is associated with reduced mortalityTrial OR

Coronary Drug Project Research Group (1980) 0.45

β Blocker Heart Attack Trial – Men (1990) 0.41

β Blocker Heart Attack Trial – Women (1993) 0.31

Canadian Amiodarone MI Arrhythmia Trial (1999) 0.45

Cardiac Arrhythmia Suppression Trial ( 1996) 1.54

Physicians Health Study (1994) 0.70

West of Scotland Prevention Study (1997) 0.85

University Group Diabetes Project (1970, 1971) 0.43

Overall 0.56

Simpson, et al. A meta analysis of the association between adherence to drug therapy and mortality. BMJ. 2006.

Odds Ratios for Mortality with 95% CI

Adherence to placebo is associated with reduced mortality

Odds Ratios for Mortality with 95% CI Every one of these results refers to

those participants in the placebo group, not the group that received the active drug.

Because these effects are seen with placebo use, they suggest that good adherence is a marker for otherwise unmeasured healthy behaviors.

Adherence to placebo doesn’t cause good health. It reflects good health behaviors.

Intrusiveness versus accuracy

The measurement of behavior can also introduce selection.

Accurate measures are often intrusive.

Seamless measurement or unnoticed measurement is the ideal.

There are biometric and human subject protection challenges to this ideal.

Organizing questions

How do we determine what influences behavior change in real world settings?

How do we measure meaningful behavior change so that the measurement is not the selecting or influencing effect (unless we want it to be)?

How do we create the “quantified self” for those who would otherwise not plan to be quantified?