Diagnose a rise-then-fall in Instagram Stories engagement that keeps falling in Spain

You are a product manager on Instagram Stories. In two markets, the US and Spain, the Stories engagement rate climbed by about 10% over a 7-day period and then fell by about 10% across the following 30 days. Since then the two markets have split: the US rate has stopped falling and is holding steady, but the rate in Spain keeps dropping. What would you do? Explain how you would find the cause and what action you would take in each market. ```hint Read the shape before the causes Ask what kind of change produces a short lift followed by a longer decline, and work out where the US has settled compared with where it started. Then look for whatever is still happening in Spain but no longer in the US. ``` ### Clarifying Questions - What happened at the start of the 7-day lift: a feature launch, a ranking or ad-load change, a marketing campaign in these two countries, a local event, or nothing that we know of? - How is the engagement rate defined: interactions such as replies, reactions, sticker taps and shares per story view, per viewer, or per daily active user? Are both 10% moves relative changes? - Did other countries move over the same weeks, and have total Stories views and stories posted risen or fallen alongside the rate? ### What a Strong Answer Covers - A careful reading of the metric and the timeline: where each market ends up against its starting level, and whether the rate moved through its numerator or its denominator - Checks that rule out logging, definition or pipeline problems, including ones that would affect only Spain - A structured search for causes across internal changes that reached these two markets, shifts in the mix of users or content, and external factors in Spain - Segmentation that locates Spain's ongoing decline, such as platform and app version, new versus existing users, content source and region - A concrete decision for each market, with the evidence and guardrail metrics that would justify it ### Follow-up Questions - Suppose the lift came from a new Stories feature tested only in these two countries. How would you decide whether to keep, change or roll it back in Spain? - In Spain the rate keeps falling but the total number of Stories interactions is flat. Is that a problem, and what would you check next? - How would you set up monitoring so that a slow decline confined to one country is caught within days instead of a month?