Health Psychology, 2nd Edition

STRESS THEORY AND RESEARCH 55

Using diaries in health psychology research

Approaches to studying stress differ in their focus. For example, compare the life

events approach with the transactional approach. The life events approach has

been criticized on methodological grounds and stress research, like other areas in

health, social and clinical psychology, has been criticized for over-reliance on cross-

sectional, ‘snap-shot’ methodologies (see Affleck et al., 1999; Nezlek, 2001 for

further discussion). For example, research into the impact of stress on eating

behaviour has tended to use laboratory-based methods, which employ single

measures of stress (e.g. life events over the previous year) or one-off retrospective

measurements of stress in the short term (e.g. perceptions of stress over the past

two weeks). Such research ignores the substantial evidence showing that changes

in within-person stressful daily hassles are important in understanding stress-

outcome processes (see Bolger, Davis and Rafaeli, 2003; Bolger and Laurenceau,

2013).

We are often interested in investigating causal relationships between study

variables and/or determining whether a particular psychological variable influences a

later health outcome, e.g. on the following day or week (known as a lagged effect).

Imagine we wanted to find out if negative mood was associated with the onset of

pain episodes in arthritis patients or whether in psoriasis patients, stressful events

on one day could trigger ‘flare ups’ the next day. Conventional cross-sectional or

longitudinal study designs would not be very useful here because they miss the

detailed daily variation driving the causal processes we are interested in. In these

cases and others in health psychology research, the dependent variable under

investigation is a daily process, that is, it changes from day to day and/or frequently

within days. Therefore, in order to assess it we need to measure it repeatedly

during and over several days. A diary approach is ideally suited to such research.

What are the advantages of using diary designs and measuring daily processes?

Affleck et al.(1999: 747) argue that daily diary studies allow researchers to

• capture as closely as possible the ‘real-time’ occurrences or moments of
  change (in study variables);


• reduce recall bias;


• mitigate some forms of confounding by using participants as their own
  controls; and


• establish temporal precedence to strengthen causal inferences.

In addition, using daily diaries permits researchers to use sophisticated statistical

techniques (e.g. hierarchical linear modelling) to examine day-to-day within-person

effects together with the impact of between-person factors such as personality or

gender.

RESEARCH METHODS 3.2