The Monopoly Politics 2002 report contains two Microsoft Excel spreadsheets. The first, mp2002.xls, makes projections in the 2002 House races. The second, mp1996-2000, makes projections for each House race from 1996 to 2000 and compares the projections to the actual results in those races.
This user's guide describes how to modify the parameters in the model and analyze their impact on the projections and, in the case of 1996-2000, their accuracy.
The spreadsheets use the same algorithm for making projections. For details of the model, check out the file, algorithm.doc, which explains each parameter in greater detail.
If you have questions or problems with the spreadsheet, please contact:
Center for Voting and Democracy
Part 1: Monopoly Politics 2002 Projections
You can do 4 things with this spreadsheet:
Modify parameters to examine their impact on projections
Enter 2002 results
Views summaries of projections by category and party
View summaries of the accuracy of the projections
1. Modifying parameters
The spreadsheet contains all of the data used to make projections: partisanship of the district, which seats are open seats, date of election of incumbents, and prior 2 election results.
It also contains the following parameters that the user can modify by typing a new number into the specified cell:
Parameter Cell Default value Range
Buffer for open seats A4 11% 0-25%
Increase for underachievers A5 33% 0-100%
Decrease for overachievers A6 67% 0-100%
Reduction for underachievers A7 1% 0-25%
Previous race uncontested A8 35% 0-100%
Decrease for long term overachievers A9 60% 0-100%
Adjustment to better 2nd election A10 33% 0-100%
No proj win H4 3% 0-30%
Win H5 5% 0-30%
Comfortable H6 10% 0-30%
Landslide H7 >10% 0-30%
Dem 2-party share H9 50% 0-100%
If you enter a value outside of the range of a parameter, the projections may not be meaningful.
2. Enter 2002 results
The spreadsheet is set up so that you can enter the winning party (D, R or I) and percent in columns N and O, rows 15 to 449. Once you do that, summaries showing the accuracy of the projections will automatically appear.
Be sure to enter the winning percentage as a percent (ie, 43.7%, not 43.7, which would appear as 4370%). To enter a party, use a capital letter: D, R or I.
3. View summaries of projections
A variety of summary information about the projections appears in yellow-shaded cells in columns R-S and AA-AF in rows 1 to 10 of the spreadsheet.
Columns R-S: Total number of projections by category
Landslide: The number of projected landslide victories.
Comfortable: The number of projected comfortable victories.
Win: The number of projected wins.
Most vulnerable: The number of “most vulnerable” incumbents.
No proj win: The number of districts in which we do not project a win.
Other: This is a check for errors. It is the number of districts that do not fall in the above categories. If it is not zero, there is a problem with the model or the parameters. Please contact the Center if this happens.
Columns AA-AF: Projections by party
This table shows the projections by category for seats held by each party. These figures are based on the incumbent party, and since this is a redistricting year, some of the new seats don’t have incumbent parties. Also, one seat (VT-1) is held by an Independent. That’s why the total number of seats is less than 435.
4. View summaries of the accuracy of projection
Columns M-P: Totals of vulnerable, losing and open seats
Most vulnerable: This lists the number of projections labeled as “Most vulnerable” and, once data on the 2002 results is entered, the number of those incumbents who lost.
Losers (not open): After 2002 results are entered, this will show the number of losing incumbents.
Open seat party changes: The number of open seats whose party changed as a result of the 2002 election.
Open seats: The number of open seats this year (49).
Columns T-U: Accuracy of projections by category
These columns remain zero until 2002 results are entered.
For each of the projection categories, these columns list the number of projections in which the party projection was accurate and the number in which the winning margin was correct.
Columns V-Y: Results of races by prediction category
For each prediction category, these columns show the number of races that ended up being landslide, comfortable, wins or losses (from the perspective of the incumbent party).
The cells highlighted purple indicate races where the winning margin or party was wrong.
For example, with the default settings, there are 100 projected comfortable races. After entering the results (party and winning percent) from the 2002 races in column N and O, you will see in columns V-Y the results in the 100 projected comfortable races. Some of those races will be won by landslide, others by comfortable margins and others by less than comfortable margins. Any remaining races in this category would be losses for the incumbent.
Part 2: Monopoly Politics Projections 1996-2000
This spreadsheet works the exactly the same as the 2002 spreadsheet, except that the user can enter the desired year (1996, 1998 or 2000) in cell A4, and all of the election results are already stored in the spreadsheet, so the summaries of the accuracy of projections appear instantaneously.
We hope you find these spreadsheets useful. Please bring to our attention any data errors or other problems you encounter.