INSTRUCTIONS FOR DESIGNING GAMES

  1. Strategic Form Games for Two Players
  2. Creating a New Game
    1. Determining the set of pure strategies
    2. Labeling Strategies
    3. Labeling Players
    4. Determining Payoffs
    5. Giving the Game a Title
    6. Testing a Game

  3. Saving a Matrix
    1. Saving a New Matrix
    2. Saving an Existing Matrix

  4. Running an Experiment
    1. Determining Session Parameters
    2. Monitoring the Game

  5. Instructions to Subjects
    1. Connecting Subjects to the Experiment
    2. Registering for a Game
    3. Waiting for other Subjects
    4. Choosing Strategies

 

  1. Strategic Form Games for Two Players

There are three buttons: on the strategic form game window.

  • Click to create a new game or update an existing game in strategic form:

 

  • Click to test the game before running a session.

  • Click to view the frequency with which cells are selected by subjects during the session.

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  1. Creating a New Game

  1. Determining the set of pure strategies
  2. Click the plus sign in: to increase the number of strategies of a row player by one. Similarly, click the plus sign in: to increase the number of strategies of a column player by one. Click the minus sign: to reduce the number of strategies of a row player by one. Click the minus in: to reduce the number of strategies of a column player by one.

    Strategies are labeled in alphabetical order, as the picture below shows:

    Two Strategies C and D were added for the row player, and one strategy C was added for the column player.

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  1. Labeling Strategies
  2. To rename a strategy, click its name in the Content cell:

    In our example the strategy of the column player is highlighted, and automatically brought into the Edit mode:

    at the top of the panel. Write a new name in the Content cell:

    and press return, or click another strategy to be renamed.

    The strategy previously labeled A for the column player has been changed to Donít Confess by writing Donít Confess in the Content cell.

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  1. Labeling Players
  2. The players have default names called Row Player and Column Player. To change the column playerís name, click Column Player to highlight the default name and bring Column Player into the Edit mode at the top.

    Write a new name in the Content cell (in our example Prisoner 2) and press return, or click another cell to be edited.

    The row playerís name can be changed in a similar way.

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  1. Determining Payoffs
  2. Payoffs for a row player are in blue, and payoffs for a column player are in red. By default all the payoffs are set to zero. To change the payoffs of a row player, click the appropriate payoff. Note that the payoff is highlighted in green.

    Upon writing a new payoff of the row player in the Content cell, the changed payoff replaces the default payoff.

    Note that the Edit cell:

    indicates the row and the column number for the payoff about to be changed. In the example above the Row Payoff 1,1 has been changed to Ė2. All the other payoffs can be changed in a similar way. To move forward from one payoff cell to another use the Tab, to move back use the Shift Tab, or use the mouse by clicking the appropriate cell.

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  1. Giving the Game a Title
  2. Write the name of the game in the Title cell.

    This information will appear when server is run as in the example below, and also in the output file.

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  1. Testing a Game

Moderators have an option to click to test the game before running a session.

After choosing a strategy for each player, click the button. The original matrix will appear, showing the test has been successfully completed.

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  1. Saving a Matrix

  1. Saving a New Matrix
  • From the File menu, choose Save or Save As.
  • In the File name box, type a name of the file with "sfg" after the period. The program saves the matrix in the current drive and directory. (The default name is noname.sfg.)
  • If the matrix is saved in a different drive or directory, select either a drive and a directory, or type a file name in a File name cell.
  • Click the button.

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  1. Saving an Existing Matrix

  • From the File menu, choose Save.
  • In the File name box, the name of the existing matrix appears. The program saves the matrix under the existing name in the current drive and directory. To change the name type a new name in the File name box.
  • Click the button.

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  1. Running an Experiment

To run an experiment follow, the procedure described below:

  • Click on File menu and select Open.
  • Choose the saved file representing the game to run.
  • Click on the File menu, and select Run Server option.

  • The window with Game Server Properties appears on the screen as:

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  1. Determining Session Parameters
  • The Session identification cell is for typing a name for the game.
  • To design the game with a predetermined number of rounds with fixed player's roles, type the number of rounds in the Rounds/Fixed cell:

  • To design a game with a random number of rounds with fixed player's roles, type the conditional probability of continuing the game from one round to the next in the Rounds/Random cell:

  • To design a game with predetermined number of rounds with players' alternating roles, type the number of games in the Games/Fixed cell:

  • To design a game with a random number of rounds with players' alternating roles, type the conditional probability of continuing the game in the Games/Random cell:

  • To delay the start of a game until a specified number of subjects have logged on to the game, type the number in:

  • To save the results of the experiment, the output file with the default name SfgLog.html will be automatically created. To change the default name, click Browse, and change the name.

  • To start the experiment, click:

The window with the moderatorís computer address appears on the screen:

Provide this address to subjects in order for them to connect to the experiment. In our example the address is:

If the moderator runs several games from the same computer simultaneously or sequentially, the number at the end of the address successively increases by units.

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    1. Monitoring the Game

The moderator follows the game on the window that opens after clicking "Start":

The three buttons: Server, the Game, and Results monitor different features of the session.

  • Clicking shows how many users are playing the game, their identification, the time, their connection, when each one disconnects and who disconnects, how many connections are established, and how many connections per subjects are established.
  • In our example click the button to follow the matching of subjects through the session, the strategies each subject selected, payoffs for each round and cumulative payoffs.

  • Click to follow the frequency of each cell which is continuously updated:

  • Open an Excel or a browser, and open the file Sfglog.html where the raw data is saved. The first part of the output file consists of the raw data.

  • To view a summary of the results and the strategies played, close the server.

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  1. Instructions to Subjects

  1. Connecting Subjects to the Experiment
Subjects should open Internet Explorer 5.0 (or later) or Netscape 4.7 (or later). Then subjects should type the address that appear in the moderatorís server:
In our example, the URL at the moderator server is:

This is also the address that subjects should type on the browser, before pressing Return key:

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  1. Registering for a Game
After connecting to the address, subjects are required to register for the session:

  • Type a name or an ID number in the User name box, and the institution or affiliation in the Organization box. Then click Start Session.

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  1. Waiting for other Subjects
After registering for a session, a subject who is not yet paired with another subject will receive the following message on the screen:

When the minimum number of subjects are connected to the game, the matrix appears on the screen, and they are matched. Only then are subjects assigned a player role.

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  1. Choosing Strategies

At the bottom a randomly assigned playerís name appears. In our example, a subject was assigned to be "Prisoner 1".

Subjects should click on the cell or labels to select the strategy. The Row player strategies are always colored in blue, and the Column Player strategies are always colored in red. If a subject is assigned to be a row player the column labels are disabled, and vice versa.

When a subject makes a choice the row/column is highlighted:

When both subjects make a choice, the cell that is the intersection of the selected row and the selected column is highlighted in green:

If a subject is disconnected from the game, he or she receives the following message:

If a subject clicks Yes then the subject that was paired with the disconnected subject receives the following message:

If the disconnected subject reconnects then the subjects receives the following message:

and the matched subject who waited receives the following message:

 

When the game is over, the following message appears:

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