This article looks at how the rent prices for office spaces in big Swedish cities were related over several years. Researchers analyzed rent agreements to figure out what future rents might be like. They found that while forward rents and current rents usually went up together, forward rents tended to be lower than actual rent prices. This means that predictions based on forward rents might underestimate how much rents will increase in the future. Also, the study suggests that to make accurate rental price indexes, it's important to consider not only the quality of the property but also how long the rental agreement lasts.