September 12, 2017, was the launch day for Hillary Clinton's autobiographical account of the 2016 election she lost to Donald Trump, definitively entitled 'What Happened'. By midday 1669 reviews had been written on Amazon.com. By 3pm over half of the reviews, all with 1-star ratings, had been deleted by Amazon and a new review page for the book had been set up. After Day 1, 'What Happened' had over 600 reviews and an almost perfect 5 rating. What happened?! There were good reasons to view the flood of negative reviews as suspicious. Only 20% of the reviews had a verified purchase and the ratio of 5-star to 1-star reviews – 44%-51% – was highly irregular; the vast majority of products reviewed on Amazon.com display an asymmetric bimodal (J-shaped) ratings distribution (see Hu, Pavlou and Zhang, 2009), in which there is a concentration of 4 or 5 star reviews, a number of 1-star reviews and very few 2 or 3 star reviews. The charts in Figure 2 below, originally featured in this QZ article, show the extent to which 'What Happened' was initially a ratings and purchase pattern outlier. atlas_HJnVJAL5Z2xatlas_ryGnJaL5W2x Reviews by day A line of fake review detection research has confirmed linguistic differences between authentic and deceptive reviews, although the linguistic deception cues are not consistent and vary depending on the domain and the audience (see my brief overview in this paper). Since we don't know the deception features in advance and no ground truth has been established (i.e. we don't know for sure if there was a deception), I'm going to use two unsupervised learning approaches appropriate for unlabeled data: factor analysis, to find the underlying dimensions of linguistic variation in all the reviews, followed by cluster analysis to segment the reviews into text types based on the dimensions with the hope of finding specific deception clusters. If there is a text cluster that correlates with 'burstiness' – i.e. occurs more frequently in the reviews closest to the book launch date and/or occurs repeatedly within a short time frame – then that would suggest there are specific linguistic styles and/or strategies correlated with this deceptive reviewing behaviour. The existence of such a distinct deception cluster would strongly suggest that Clinton's PR team gamed the Amazon review system (understandably, in order to counter the negative campaign against the book). Alternatively, different reviewing strategies might be distributed randomly across the review corpus and unrelated to its proximity to the book launch date. This would weaken the argument that linguistic variation in the reviews is a potential deception cue. The two scenarios are illustrated in Figure 4 below: Deception cluster hypothesis Check back here in a few days for Part 2: Results and Discussion! faux saint laurent bag