Field Days and Field Length
Susan Frede, VP Research
November, 2008
Overview
One of the main advantages of using the Internet to collect marketing research data is the speed at which data can be collected. The benefit of speed, however, also brings the concern that the quality of the data may be negatively impacted. As researchers we strive to understand how data and business decisions may be impacted by the day of week the field starts or by how long the field is open.
Background
In February 2008, Lightspeed Research fielded a 25-cell test to address questions around the appropriate field period for online studies. This research-on-research study involved five concepts. Each concept had five separate samples, one launched each day of the week from Monday through Friday. Respondents had seven days from the day the sample was launched to respond.
All concepts were tested monadically using identical surveys. The demographic universes were selected as appropriate for the product target market. Key concept measures included Purchase Intent, Uniqueness, Value, Liking, Believability, Quantity, and Frequency. Respondents were also asked a number of category habit and brand usage questions.
The following topics are addressed in this white paper:
- Is it necessary to include both weekends and weekdays in the field period?
- Does it matter how long the field is left open?
- Does it matter what day of the week the field starts?
Weekday vs. Weekend Responders
There are no significant differences between weekday and weekend responders on key measures (see Table 1). There are also few significant differences between weekday and weekend responders on demographics and habits. The only notable differences are on locations where surveys are typically completed and time to complete the survey. Those responding on the weekend are more likely to complete the survey at home and are less likely to take over 24 hours to complete the survey (i.e., stop the survey and return to complete it). The lack of significant differences suggests that including both weekend and weekday responders is not necessary to have a representative sample.
Length of Field
Day 1 and day 2 of the field have the largest proportion of completes (see Chart). There are very few completes on days 5 through 7. For this research, reminders were not sent to respondents. However, other research on research has shown that reminders don’t increase response rate significantly or improve representativeness. There are some differences in key measures depending on the day of field respondents answer the survey (see Table 2). Specifically, day 7 responders tend to give lower key measure scores. Purchase intent and key measure scores tend to be very consistent on days 1 thru 3. However, the earlier responders (especially day 1 and day 2 responders and to a lesser extent, day 3 responders) tend to be slightly different demographically. Earlier responders tend to be older and part of smaller households with no children and lower income. They are also more likely to be Caucasian and retired. Later responders (day 4-7) tend to be those who may have busier lives (i.e. employed full time, children/families). These demographic differences suggest that field should remain open at least four days in order to get a representative sample.
Purchase intent and key measures are consistent with the seven-day field period data when looking at different cumulative totals. Table 3 shows combined data for the five concepts, but even for individual concepts differences are not observed. There are also no meaningful differences on demographics and habits across these four groups. This data coupled with completion rates, suggests a four-day field period is sufficient to get stable results.
Day of Week Field Launch
In general, scores tend to be slightly lower for Thursday launches and slightly higher for Friday launches (see Table 4). However, this same pattern is not observed for all five individual concepts. In addition, the differences versus Total are generally small. In fact, only the top box uniqueness score on Thursday is greater than +/-2 versus Total. Coupled with no meaningful demographic and habit differences across the field launch days suggests that field can be started any day of the week.
Conclusions and Recommendations
Based on this research on research, Lightspeed Research recommends a minimum of a four-day field period. This leads to more representative samples and ultimately more accurate data and business decisions.
The day the field launches does not appear to impact data and there is no difference between those responding on the weekend versus during the week. Therefore, there is no need to launch on a consistent day of the week or include both weekends and weekdays in the field period. The one exception to this recommendation is when there is a need to track scheduled marketing activity. For example, there may be a need to get immediate reaction to a new television advertisement.
About Lightspeed Research
Lightspeed Research (www.lightspeedresearch.com) is the market researcher’s choice for digitally accessing and deriving insight from consumer opinions and behaviors whenever, wherever and in whatever segments needed. The industry’s most thorough panelist prescreening process and large global pool delivers business-ready results quickly and costeffectively. From proprietary online access panels to specialty panels, custom panels and innovative mobile surveys, Lightspeed Research offers the industry’s highest-quality and most complete combination of qualitative and quantitative online research. This is backed by an expert client operations team that provides a range of data collection services, from sample management and survey design to programming and reporting. Part of Kantar, a division of WPP, Lightspeed Research serves clients and cultivates online panelists across the Americas, Europe and Asia Pacific.
Susan Frede is the VP of Research at Lightspeed Research. She has worked in the research field for 23 years, has published numerous research-on-research papers and is a well-respected speaker at key industry events. Some of the topics she has recently explored include questionnaire length, best practices for online research, suspicious and professional respondents and data stability. You can contact Susan at sfrede@lightspeedresearch.com
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