Mar 17 2008

Homework #1

Published by Briggs at 1:37 pm under Bad statistics, Good Statistics

I was reminded of this homework problem that I give my students as I was riding in on the F train this morning. It is a very good problem because it is exceedingly simple and nicely demonstrates two problems of the classical way of looking at statistics.

All you need to do this homework is a busy place and some free time, about 20 minutes.

Find a spot where people congregate or pass by. Be sure to carefully and concretely specify this place: keep its boundaries fixed and rigid for the duration of the homework.

Count the people in the spot, either all at once, or as they pass by for some fixed time (decided in advance). Also count the number of people who are wearing some sort of thinking-suppression device. There are obviously any number of other things you can take note of, like sex, age, etc., but we’ll ignore all of them.

Report back to me (in the Comments) the two numbers, number wearing thinking-suppression devices, which will be less than or equal to the total number of people. Also note details of your spot.

We are obviously going to be talking about forming ratios and estimating probabilities. I’ll discuss what all this means–and what it does not mean—once a few people have turned in the assignment.

Oh, yes. A thinking-suppression device is anything like an I-Pod, MP3 player, etc. etc.

14 Responses to “Homework #1”

  1. Bernieon 17 Mar 2008 at 2:49 pm

    How do I categorize a cell phone? Is it a thinking-suppression device or a thought projection device or both? I ask because since it can be unclear whether an earpiece is for a music player or cell-phone or both? Does this question matter for the assignment?

  2. Larry Sheldonon 17 Mar 2008 at 3:10 pm

    Teacher riding the “F” train.

    Heh.

    I would have said that thought is orthogonal to the devices named, and their kith.

  3. Briggson 17 Mar 2008 at 3:33 pm

    Bernie,

    Excellent question.

    Larry,

    You wouldn’t say that if you would have seen my last class.

    Briggs

  4. Demesureon 17 Mar 2008 at 3:42 pm

    I have a live webcam in Lahsa/Tibet, and I count a lot of machine guns
    Is a machine gun a thinking-suppression device ?

  5. Steve Hempellon 17 Mar 2008 at 6:32 pm

    Homework Assignment

    Live in a small town so “busy” is hard to find.

    Time 30 minutes from 14:58 to 15:28, Population of town ~2300, 12 Deg C, Sunny with cloudy periods. Spring Break ie no teenagers milling around after school.

    People passing by 41 (counted only once)

    People with thinking-suppression device 1

    Area surveyed - Sat on bench on main street. People had to pass by me from one side to the other behind me, across the street or walk in the crosswalk just to one side of me.

    Probably not a good sample size, but it did my homework and the dog didn’t eat it!

  6. Tim Jameson 18 Mar 2008 at 7:59 am

    Here’s my homework:

    Total sample size: 373
    Those wearing TSDs: 30

    Position: Camden High St. exit of Camden Town Underground. Time: 12:03 - 12:23 Date: 18/3/08

    It’s been a long time since I handed in homework. Are stars still awarded?

  7. Briggson 18 Mar 2008 at 8:57 am

    Tim & Steve, you both get two gold stars. And one red one. I hoping for a few more answers before I post the answer.

  8. JH Sepanskion 18 Mar 2008 at 10:31 am

    Five minutes before my class started.

    12 students, 1 with TSD

    Please don’t tell me that there is no unique answer to this homework. I know for sure mine is the right one.

  9. Sven T?rpeon 18 Mar 2008 at 12:26 pm

    2008-03-18 11:46 CET, inside the rear section of light rail from $SMALL_TOWN to $LARGER_TOWN, in between two stops.

    6 persons (including myself), 1 actively using a cellphone. I cannot tell whether the cellphone worked as a thinking-suppression device as she was speaking Russian.

    One stop and one minute earlier it would have been 4/0, should that matter.

  10. Steve Hempellon 18 Mar 2008 at 2:07 pm

    Addendum to homework assignment:

    One other person was wearing a thinking-suppression device but was not “plugged in”. My criteria was that the device had to be plugged into their ears. Actually they plugged it in when they passed on the other side of the road, but that didn’t count either.

  11. Bernieon 18 Mar 2008 at 7:31 pm

    Matt:
    Quit grinning. Don’t go professorial on me. What is the answer to the question.

  12. W J Bon 19 Mar 2008 at 2:22 am

    Coffee Shop patio near office. Roughly 20 minutes. I’m gonna say about 25 outside tables equipped with three seats each litter the area. Only counted MP3 players and video games–phones aren’t TSD right?

    26: 103

    *In Shanghai a lot of girls read books/articles on there Nintendo DS’. No way of knowing the thoughts supressed or created.

  13. Chrison 19 Mar 2008 at 11:50 am

    Would that include the Blackberry I am using to read this right now?

  14. GeorgeMon 19 Mar 2008 at 7:03 pm

    While my wife shopped in one store in the mall, I sat on a bench out front and counted 105 people passing by in front of me. 100 were unencumbered, 3 women and 2 men were actively conversing on cell phones. Elapsed time, about 15 minutes.

    Amazingly, I saw not one IPOD or other device with earphones or whatever thay are called during the entire time we were in the mall.

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