//  File MIT-Lab-03-02-00-02.txt. Edition 12/29/2012.


//  Lab Specs
//    Title
        Opinion_Poll_Simulation
//    List of Population Proportions
        .1 .9 .1 .5
//    List of Sample Sizes
        1_2_3_4_10_16_25_50_100_200_400
//    List of From Bounds - Decimals
        0.000  1.000  .025  .000
//    List of To Bounds - Decimals
        0.000  1.000  .025  .500
//    List of From Bounds - Integers
        0 -1 1 -1
//    List of To Bounds - Integers
        0 -1 1 -1


//  Problem Specs
//    ActFrac
//    SampleSize
//    PauseCheckbox(-1 checked 0 cleared)
//    NonRandomSampleCheckbox(-1 visible unchecked, 0 not visible, 1 visible checked)
//    To-FromValues(0 hide, -1 reset values to none, 1 leave current values intact)


` .5 100 -1 0 -1
Objective: Show that when the estimated fraction's probability distribution is symmetric,
 the chances that the estimated fraction will be less than the actual population fraction in any
 one poll equal the chances that the estimated fraction will be greater than
 the actual fraction.
_
The actual population fraction equals.5. The election is a tossup. Half the population
 supports Clint and half does  not. The sample size equals 100.
` .5 100 -1 0 -1.

Note that two new lists have appeared in the lower left of the window: a From list and a To list.
 By default, a From value of .000 and a To value of .500 are selected. The From-To Percent line
 reports the percent of repetitions in which the estimated fraction lies
 between the From value, .000, and the To value, .500.
_
Click Start. What is the estimated fraction from the first repetition? Next,
 click Continue a few times to convince yourself that the simulation is
 calculating the From-To percent correctly.
 

` .5 100 0 0 1
2. Be certain that the Pause checkbox is cleared. Click Start and then,
 after many, many repetitions, click Stop. What percent of the repetitions
 fell between .000 and .500?
_
4. Recall that the actual population fraaction, ActFrac, equals .5. How do the chances
 that the estimate from one poll will be too high
 compare with the chances that the estimate will be too low? Explain.
_
5. Does the estimation procedure systematically underestimate or overestimate
 the actual population fraction? Explain.