Reference answer
1. Define the business objective
First, you should start by making sure you understand the product properly and agree with your interviewer on specific user and business objectives. Agreeing on the goals upfront is extremely important because your priorities will change depending on what you're trying to achieve with the product.
In this instance, given that we've been informed we're the PM for a brand new mobile app, the current business objective could be to drive new user acquisition and engagement. Let's assume that we've run this by the interviewer, and they've encouraged you to focus on user engagement.
Now that we know what we're working toward, let's apply a prioritization framework to our three options.
2. RICE Framework - Reach
First, we'll determine the Reach for these three projects. For project A, the in-app messaging update, we know that every user who sent messages will be impacted by this change. Let's say that the interviewer has given us some general numbers to work with, so we know that an average of 250 users have sent messages each month over the last quarter.
Project B (desktop app) will be more difficult to estimate, as we do not have any concrete numbers to back up how many users will take advantage of the desktop version. Let's say that we've checked with our interviewer and have been informed that our early user base is around 700. Using a more conservative estimate, we guess that 50% of them will use the desktop app. That brings us to 350.
Finally, as project C is adding a cropping tool to the free category of our full editing suite, we can count the number of users who may implement it. It's a simple, commonly used tool, so we can assume the majority of users will use it, so we'll round the Reach number to 600.
So here is our breakdown for Reach:
Project A: 250
Project B: 350
Project C: 600
3. RICE framework - Impact
For project A (messaging update), let's say that the interviewer has informed us that users who send messages appear to do so sporadically. They use it to share edited photos with friends who also use the app, something that users are already able to do through the share feature. So, as users who do make use of the messaging system don't engage with it heavily, let's say the impact is low, giving us an Impact score of 0.5.
For project B (desktop app), this feature will have a huge impact on users who adopt the desktop version. Thus the Impact score is 3.
Finally, project C involves adding a simple cropping tool to the editing features that are available to all users. However, as it is a relatively small addition to the toolset, rather than a complete overhaul, we can assume the impact wouldn't be "huge." Let's choose the "high" Impact score of 2.
So here is our breakdown for Impact:
Project A: 0.5
Project B: 3
Project C: 2
4. RICE framework - Confidence
Our Reach value for Project A (messaging update) is concrete and data-based, using the given number of users who send messages on the app. However, we are largely estimating Impact, as we do not yet have the data in the interview setting to back up those scores. We'll give project A an 80% Confidence score.
We've been given less data on Project B (desktop app) versus project A, meaning we had to make estimations for Reach and Impact. So project B has a low 50% Confidence score.
We do have a data-based value for Reach in Project C (cropping tool) but not for Impact. So project C will also have a Confidence score of 80%.
Here is our breakdown for Confidence:
Project A: 80%
Project B: 50%
Project C: 80%
5. RICE framework - Effort
Let's say that there's already a framework in place for the messaging update, so the timeline of Project A won't take longer than one person-month. This will bring us to an Effort score of 1.
Project B, designing an entire desktop app, will require a much larger time investment from the whole team. Let's imagine that you've worked on a similar project in your past experience, and that it took six person-months to complete. You should acknowledge to your interviewer that, of course, this is an imperfect comparison. But given the limited information you have in an interview setting, we'll take this as an Effort score of 6.
For Project C (cropping tool), let's say that the interviewer has told us that the team's previous time investment for adding new editing features was three person-months. So we'll give project C an Effort score of 3.
Here is our breakdown for Effort:
Project A: 1
Project B: 6
Project C: 3
6. Re-evaluate and consider trade-offs
When we take the four previous values and run them through the RICE formula for each project, here is what we find:
Project A: (250 x 0.5 x .80) / 1 = 100
Project B: (350 x 3 x .50) / 6 = 88
Project C: (600 x 2 x .80) / 3 = 320
So, if we only take the RICE score into account, we should prioritize Project C (cropping tool), then Project A (messaging update), and put Project B (desktop app) at the lowest priority. However, we know that estimations won't be 100% accurate, especially given the limited information in an interview setting. Consider any other factors that should be taken into account, such as time-sensitive dependencies for other projects.
In this case, prioritizing the cropping tool makes sense, as the ability to crop photos in an editing app is a basic attribute that many users would expect to be able to access. The trade-offs to consider when prioritizing project C would be that offering a crop tool as a free feature may lead fewer users to upgrade to a paid account; however, it would be riskier to withhold the feature, for fear that users migrate to different apps.
As Project A (messaging update) and project B (desktop app) have similar RICE scores, this would be a good time to investigate whether there are any other reasons to prioritize one over the other. Let's imagine that the interviewer mentioned that a desktop application was an early promise they made to stakeholders when initially launching the product. In this case, it would make more sense to prioritize Project B over Project A, despite the order of their RICE scores.
So, in this context, we should prioritize the projects in this order: C, then B, then A. However, there is no single correct answer for prioritization questions. You may come to a different conclusion than we did, or use a different framework such as the Kano model. The interviewer wants to see that you have a method for making choices and trade-offs, and that you're considering the most relevant factors.