Let's say you have a new business idea and you want to see if it is worth putting any more time into. You've told a few people about it and some say it's a good idea (maybe out of kindness) and some say it isn't. But none of that really means anything. So how can you start? Traditionally people suggest writing a business plan. These are 20+ page essays full of untested assumptions that take 80 hours to write. I know 'cause I've written them before. As Steve Blank says "No business plan survives first contact with customers." He suggests the lean startup approach, going the the loop of build->measure->learn->build, etc. developed by Eric Ries.
This became connected with the lean business model canvas. Here are slides on how to fill it out: https://www.slideshare.net/de-pe/lean-canvas-process-and-examples
The lean canvas fits the build measure learn loop. You build a solution to the problem, then measure the solution using the key metrics, from which you learn a more nuanced view of the problem and cycle continues.
I put together a template with examples in google docs here.
I have also found the Sequoia pitch deck format to be a useful starting place to think about whether a business idea has legs. Entrepreneurs often think a pitch deck is for investors, but that's not quite true. A good pitch deck should be written not to appease the investors, but as a way for an entrepreneur to dig through the important issues of a business in a way that the investor can start to evaluate if it make sense for them. You can't hide the main issues with your business; even a mildly savvy investor will be able to figure that out. So a good pitch deck is not written for the investor. It is written for the entrepreneur for the investor, if that make sense.
Below is a template for the Sequoia pitch deck and I've made a template in Google Drive that you can edit here.
Simplify a system down to a 2x2 matrix and it says a lot about the system. These are useful to dissect a competitive landscape, understand society and understand religion.
Peter Thiel famously used 2x2 matrices to understand the innovativeness of cultures at a societal and company level in Zero to One. It's also common for competitor analysis and it makes an otherwise completely subjective act of comparing yourself to other companies ("company A doesn't have [very niche feature] but we do.") to a relative act where you can decide if the comparisons are valid and if the axes of measurement are relevant e.g. maybe a very niche feature isn't a relevant point of comparison. The early Airbnb and LinkedIn pitch decks use a 2x2 matrix this way.
More interestingly on a societal level 2x2 matrices uncover what is going on below the surface. These insights I attribute to Jim Keller who I am sure can attribute some of these to other people as well.
In a society there is a king, his ministers and the people. The king has power and money of course, the ministers have money, yes, but no power as they are totally at the mercy of the king. The people have neither money nor power. This looks like a stable system. However, when there is three of anything consider that there is a hidden fourth quadrant. If you break down the three into constituent parts you can find the hidden fourth.
The Hero is the hidden fourth and derives his/her power not from money or status but from the people. He/she is the one able to overthrow the king. While the king is always worried about the ministers, his real threat is the hero.