Researchers developed a method to figure out what people like to buy even when some choices are hidden. They used data on what people actually bought to guess what other options they might have considered. By doing this, they were able to understand people's preferences without needing to know how they decided on their choices. They tested this method by looking at how much people in the UK like to buy chocolate bars on-the-go. They found that not considering hidden choices can lead to big mistakes in understanding what people like to buy.