Exhaustive research of the public domain supported the findings of the original research brief: namely, that there is no information publicly available which directly answers your question. However, our continued research did discover that airline price drops happen predictably at 21, 14 and 7 days post-purchase, and that hotel price drops seem to follow a similar schedule. Below you'll find our methodology and related findings.
Similar to the previous research, we found that there are no consumer insight or market research reports published which canvass the topic of consumer experiences of price drops and associated statistics, nor of price drops across industries. This is largely because the type of information requested appears to be available only via primary market research, and no such research has been publicly published. For this reason, we chose a similar but different research strategy: we searched for information about price drops within 1-14 days, in specific industries, irrespective of the customer's experience.
Within our available time frame, we were able to research the retail, travel and hospitality, and electronics sectors. We began with searches for consumer insight and market research specific to these industries and price drops, but this strategy didn't generate any directly relevant information. All indirectly related information has been detailed in the 'Related Findings' section. However, this research did generate a source listing price tracking apps. Using this source and a second, longer list of such apps, we researched each app's website and associated blog individually, on the assumption that such websites might contain reports, statistics or other useful data about price drops. Of the 10 apps researched, only one (Yapta) had any related information, which is detailed below in the 'Travel and Hospitality' sector.
PRICE DROPS AND PRICE ADJUSTMENTS
In the industry, price drops are very frequently referenced in the context of price adjustments, wherein a retailer refunds the customer the difference between the original price paid by the customer and the dropped price. Our research discovered that there is a fair amount of variability in retailer price adjustment policies. 27% of surveyed respondents will give a price adjustment within a 14-day window; only 3% extend that to 30 days. Interestingly, only 5% of customers are willing to ask for a price match - which, though different from a price adjustment, shows the consumer's relatively low level of engagement around price negotiation.
Price tracking apps vary in what they track and in which retailers/vendors they monitor, but they all essentially perform the same function: to track the changes in price and alert users to the price differential. Apps researched include Paribus, CitiPrice Rewind, Yapta, and Earny, among others. Of the researched apps, only Yapta had a published white paper with hard data available.
TRAVEL AND HOSPITALITY SECTOR
Yapta's 2017 white paper on 'Airfare and Hotel Rate Volatility' is very specific to the corporate market. In that context, it indicates the following, relative to price drops in the airfare and hotel sectors:
Airfare price drops are consistent and predictable, coming at 21, 14 and 7 days in advance of departure date. "The data reveals that 29% of airlines’ price drops occur 21 days or more in advance, dropping to 16% in the time frame 15-21 days in advance, followed by an increase to 27% eight-14 days prior to departure, then returning to 29% within one week of departure...This conforms with airlines’ historical yield management practices of the 21-day, 14-day, and 7-day advance purchase windows."
The paper also notes that hotel prices follow a similar 14- and 7-day advance pricing drop, though the overall change in room rates is minimal. It should be noted that this paper examines dynamic pricing, which is the movement of pricing both up and down; but it is referenced as the only example of hard data on price volatility.
To wrap it up: extensive research indicates that there is insufficient information in the public domain to answer your query. Available data on dynamic pricing in the travel and hospitality industries indicate that airline price drops happen on a predictable pattern, and that hotel price drops mirror that pattern.