 39. Ecological Sampling Methods  809
important to study personality directly in 
everyday life.
Ecological Assessment of  Daily  Experiences
The long history of ecological assessment 
of daily experiences started with unsystem -
atic daily diaries of people’s leisure activi -
ties or money management (Bevans, 1913; 
for an overview see Lewin, 1951). The first 
systematic daily self-  report questionnaires 
on emotional experiences or social interac -
tions emerged in the late 1970s (Csikszent -
mihalyi, Larson, & Prescott, 1977; Wheeler 
& Nezlek, 1977). Researchers used elec -
tronic paging devices as a reminder to col -
lect paper-  pencil questionnaires at random 
time points during the day (Csikszentmih -
alyi et al., 1977). In the following decades, 
more advanced computer-  based assessments 
via handheld-  computers and smartphones 
replaced the classic paper-and-  pencil ques -
tionnaire (Bolger & Schilling, 1991; Pawlik 
& Buse, 1982). Conceptually, repeated daily 
life assessments comprise both experience 
sampling  and daily diary methods .
Experience Sampling and  Daily Diary  Methods
Experience sampling methods  (ESM) refer 
to assessment of people’s experiences mul -
tiple times per day over several days or 
weeks and typically focus on not only self- 
reports of emotion and thoughts, but also 
perceived behavior and situation (Hektner 
et al., 2007). In contrast, daily diary meth -
ods require participants to answer a ques -
tionnaire only once a day, typically at the 
end of the day, and to provide information 
on events and experiences during the day 
(Bolger et al., 2003). Since participants an -
swer questions only once a day, total as -
sessment periods can be longer compared 
to experience sampling studies. Most daily 
diary studies last between 7 and 30 days, 
with the majority of them lasting 2 weeks 
(Gunthert & Wenze, 2012). Similar to ex -
perience sampling, daily diary assessments 
aim at minimizing recall biases, but experi -
ences are not immediately reported; rather, 
they are reported with a few hours’ delay. 
Recall biases likely differ between psycho -
logical phenomena; for example, whether or not an argument occurred may be reported 
accurately both immediately and at the end 
of the day, but the recall of the intensity of 
the emotional experience may vary between 
immediate and delayed reports (Robinson & 
Clore, 2002). Both experience sampling and 
daily diary studies require very short ques -
tionnaires (<5 minutes) to motivate immedi -
ate responses.
Computerized assessments are preferred 
over paper-and-  pencil questionnaires for 
several reasons: (1) Data are directly elec -
tronically saved—and even immediately ac -
cessible, if the entries are uploaded directly 
onto a server—  so there are no data entry 
errors; (2) responses can be time-  stamped 
to control whether participants answered 
the questions at the specified times instead 
of all at once at the end of the day or the 
study; (3) participants can receive remind -
ers to respond to unanswered prompts; (4) 
randomized assessment times are possible 
to minimize expectancies and measurement 
reactivity (e.g., people cannot adjust their 
behavior if they do not know that an assess -
ment is coming up); and (5) multimedia and 
randomized content can be presented. One 
potential disadvantage of computer-  based 
assessments is that specific populations 
might not be able or willing to participate 
in a computer-  based study due to lack of 
technical equipment and/or skills. With the 
increasing dissemination of mobile technol -
ogy and skills to use it, this disadvantage 
will diminish.
Assessment  Schedules
For assessing experiences in daily life, re -
searchers can choose between different as -
sessment schedules: Assessments can occur 
multiple times a day (1) at fixed times, 
for example, every 2 hours (i.e., interval-  
contingent sampling ); (2) at (pseudo-) ran -
dom times, for example, every 2 hours ± a 
random number of minutes; (3) in response 
to specific events such as social interactions 
(i.e., event-  contingent sampling ); or (4) 
based on combinations of these schedules 
(Hektner et al., 2007; Moskowitz & Sadikaj, 
2012; Wheeler & Reis, 1991). The design 
choice depends on the (assumed) frequency 
and continuity of the target phenomenon. 
For example, conflicts tend to be an infre -