It was suggested I provide a concrete example from yesterday’s idea of writing a one page business case. Here it is below.

This is a very simple version, but you can see that I lay out the summary in a concise format, and then leave the details to follow. Most people will only read the summary but those that need it can follow in the details. In the details, I first lay out any assumptions and then analyze each option in a concise manner. I finish with some qualitative analysis. There could be many variations to this scenario; and, with the assumptions, someone could work those out. Instead, I pick the actual scenario (which is what I did two weeks ago) and work out the numbers.

This took me less about 20 minutes to prepare and will settle most arguments. Try this simple form of analysis and credibility will build.

Example: Should I rent a car or use taxis?

Summary:
Two weeks ago I rented a car while in New York City for four days. It was suggested I could use a taxi and save a lot of money. However, while I stayed in Manhattan I traveled to New Jersey, Connecticut, east end of Long Island and few points around the NYC. Based on a pure cost analysis it is cheaper to rent a car by but only by 12%, saving $79. If I ask the taxi to wait eliminating any waiting time (and making it equivalent to having a car on call) then the savings renting a car are $367 or 37%.

The assumption that I would have saved money is wrong and on a pure cost basis, I recommend we continue to take taxis.

The pros vs. cons of renting vs. taxi are considered. However, since the clients are remote from NYC and not clustered in the center, the convenience of having the car outweighs the other considerations. I still recommend we rent a car.

Details:
Assumptions:
I visited 7 clients and drove 500 miles in four days. I stayed in the center of Manhattan. One of the clients is in the Hamptons.
Renting a car:
Car rental: $92/day.
Parking overnight: $40/day
Parking at clients: Free
Gasoline was $88.00
Taxi rates are: $2.50 for each pickup and drop-off plus $2.00/mile
There is a luxury bus from Manhattan to the Hamptons for $65 round trip. That trip is 200 miles.
Tolls are the same whether I rented or take a Taxi.

Option A: Rent a Car
Car rental: $92/day times 4 days = $368
Parking: $40/day times 4 days = $160
Gasoline: $88
Total cost: $616

Option B: Taxi
# Taxi trips: 12
# Taxi miles: 500-200 = 300
Base taxi rate = $2.50/pickup-dropff * 12 = $30
Taxi miles = 300 miles * $2/mile = $600 miles
1 Hampton round trip: $65
Total cost: $695

Option C: Asking the Taxi to Idle
Cost of Taxi: $695
Average time with client: 2 hours
Note that we are only using a taxi with 6 clients.
Cost of waiting time: 2 hours/client * 6 clients * $0.40/min * 60 min/hour = $288
Total Cost of Taxi if they idle: $983

The pros of renting a car means you have the car when you need it, but the cons are that the car can be more trouble due to tows and you cannot easily work while you are driving. On the other hand, a taxi allows you to not worry about the car and you can work. The taxi cons are that in several of the locations there was no way to find a cab and I would have had to either wait for a cab extra time, or ask them to idle. Asking the cab to idle would add an extra $288 to the cost bringing the total to $988.