In view of recent popularity of (mis)using fancy mathematical methods for Big Data analysis, I feel a burning need to relate this Russian joke. As with many Russian jokes, this is a little long and involved, so please bear with me and read to the end.
Three mathematicians and three physicists are traveling to an out of town conference by train. They meet at the train station and go to buy tickets. The physicists are first, and buy three tickets, as expected, one for each person. The mathematicians are next, and they buy just one ticket. The physicists are confused:
"How come you only bought one ticket? There are three of you. Don't you know that each person needs a ticket? You will be booted off the train by the conductor!"
"Don't worry," say the mathematicians, "we have a method!"
Everyone gets on the train. The physicists take their seats, but they are paying close attention to the mathematicians, to see what they are going to do. The mathematicians all pile together into a single-person train bathroom. When the conductor comes by to check the tickets, he knocks on the bathroom door, which opens a crack and a hand with a ticket is extended out. The conductor takes the ticket and everyone proceeds on their merry way.
The physicists are very impressed.
After the conference, it's time to go back home, so they all go to the train station to buy tickets. The three physicists are exited to try out their newly learned trick, so they buy one ticket. They are surprised again, when they see that the mathematicians don't buy any tickets at all.
"What are you doing? Don't you need at least one ticket?" they ask.
"Don't worry," say the mathematicians, "we have a method!"
On the train, the physicists all pile together into one bathroom, the mathematicians into another bathroom. Just as the train is about to start moving, one of the mathematicians exits their bathroom, walks over to the physicists' bathroom and knocks on the door. The door opens a crack and a hand with a ticket is extended out. The mathematician takes the ticket and goes back to the mathematicians' own bathroom with it.
Moral of the story:
Do no use mathematical methods that you do not fully understand.
*******
Three mathematicians and three physicists are traveling to an out of town conference by train. They meet at the train station and go to buy tickets. The physicists are first, and buy three tickets, as expected, one for each person. The mathematicians are next, and they buy just one ticket. The physicists are confused:
"How come you only bought one ticket? There are three of you. Don't you know that each person needs a ticket? You will be booted off the train by the conductor!"
"Don't worry," say the mathematicians, "we have a method!"
Everyone gets on the train. The physicists take their seats, but they are paying close attention to the mathematicians, to see what they are going to do. The mathematicians all pile together into a single-person train bathroom. When the conductor comes by to check the tickets, he knocks on the bathroom door, which opens a crack and a hand with a ticket is extended out. The conductor takes the ticket and everyone proceeds on their merry way.
The physicists are very impressed.
After the conference, it's time to go back home, so they all go to the train station to buy tickets. The three physicists are exited to try out their newly learned trick, so they buy one ticket. They are surprised again, when they see that the mathematicians don't buy any tickets at all.
"What are you doing? Don't you need at least one ticket?" they ask.
"Don't worry," say the mathematicians, "we have a method!"
On the train, the physicists all pile together into one bathroom, the mathematicians into another bathroom. Just as the train is about to start moving, one of the mathematicians exits their bathroom, walks over to the physicists' bathroom and knocks on the door. The door opens a crack and a hand with a ticket is extended out. The mathematician takes the ticket and goes back to the mathematicians' own bathroom with it.
Moral of the story:
Do no use mathematical methods that you do not fully understand.