Stated purchase intent can anticipate consumer behaviour

by Nigel Hollis | May 13, 2019

When you have worked with survey data for over thirty years – gulp – you take for granted things that other people do not. For instance, unlike many, I tend to assume that consideration and stated purchase intent questions do anticipate consumer behaviour. However, I do not assume that an individual’s stated intentions will guarantee they buy the brand they state.

I decided to write this post after I heard yet another person decry the ability of surveys to anticipate consumer behaviour. The speaker, as with many marketers, evinced far more confidence in behavioural trend than the survey data. Uh oh, I thought, here we go again. Yet another person assuming that one single measure of attitude is going to anticipate behaviour, or rather, finding that it does not.

Now, let us be clear, there is academic evidence to suggest that measures of stated intention are not as accurate at predicting behaviour as we might like, lending credence to the general belief. But again, is the general assumption that one data point is likely to anticipate behaviour valid in and of itself? Honestly, I think it is naïve to assume that there is a direct link between stated intentions and behaviour when there are just so many ‘out of context’ factors that could influence people’s actual behaviour.

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For a start, it depends on what product category you are dealing with. Purchasing of consumer packaged goods purchases is innately variable. They are typically a repertoire purchase, with people seeking to satisfy different needs and occasions, buying for others, and dealing with the inherent vagaries introduced by out-of-stocks, in-store promotions and a desire to try something different for a change.

That said, even stated intentions of packaged goods purchase prove reasonably accurate over time. “Beneath the surface the hidden world of individual buying behaviour” by Kyle Findlay, Constantin Michael and Jan Hofmeyr (available with WARC subscription) reports an analysis which compares stated purchase intention, e.g. buy most often, against actual purchasing behaviour from panel and loyalty records and finds little relationship over three months but a far stronger relationship over 12 months. Given the chaotic influences on any individual packaged good purchase, this is hardly surprising. It takes time for people’s intentions to play out.

Similarly, while the predictive power of individual stated intentions may be relatively weak, when aggregated up their predictive capability is far stronger, as the influence of chaos tends to cancel out. Predictions can be further improved by taking into account factors known to influence the probability of purchase, like brand size (a surrogate for physical availability) and relative price (people are less likely to follow through on their intention to buy if a brand proves more expensive than its competition).

The practice of marketing is one of influencing the probability that someone will buy a specific brand (you cannot guarantee it). So why do so many people seem to assume that probabilities do not apply to stated intentions, or that one survey measure is likely to prove an adequate predictor of behaviour? Please share your thoughts.

2 comments

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  1. Nigel, May 16, 2019
    Thanks Mike, I really appreciate this build.
  2. Mike Berendes, May 13, 2019

    Our company conducts in-person, in-the-moment surveys across retail, dining, and event location in the US and Canada.  Similar to your article, we have found stated intentions, when coupled with store and brand loyalty KPIs, are a quite reliable measure of future purchase intent.  This has been borne-out via various studies we - and our clients - have conducted.  

    I think it has a lot to do with our being live and at the "moment of truth."  With no recall, consumers of products and services give clear perceptions, impressions, and feedback that give a DIRECT road-map to marketers.  It's funny, but in our technology-saturated industry, "what was old is new again" when it comes to treating people as individuals.  Coupled with being at the right time in the buying journey, we certainly can attest to the power, accuracy, and relevance of correctly-fielded surveys, interviews, and observations.

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