Appendix

This content is an excerpt from

z-Tree 3.5: Tutorial and Reference Manual
by

Urs Fischbacher, Thurgau Institute of Economics at the University of Konstanz
Katharine Bendrick, Southern Connecticut State University
Stefan Schmid, University of Zurich

Zleaf properties

• /server adr
  • adr contains the IP address of the experimenter PC.
• /name name
  • name is the name the client has in the clients’ table.
• /nameisipaddress
  • The IP address is the name the client has in the clients’ table.
• /size widthxheight
  • Size of the client’s window. In this way you can test on a large screen how the layout will look on a small screen. For example, the VGA format is 640x480. There may be no spaces around the 'x'.
• /position xpos,ypos
  • Position of the client’s window with respect to the top left corner. There may be no spaces around the comma.
• /fontsize size
  • Sets the font size.
• /fontface face
  • Sets the font face.
• /buttonfontface face
  • Sets the font face for buttons.
• /logtime
  • Stores time at which input is made or the screen is updated. It uses the time on z-Leaf. This time is therefore not influenced by network delays. On the other hand, this time is not synchronized across different subjects.
• /logtimelocal
  • The timing information is stored on a local directory on the z-Leaf computer.
• /xlsdir dir
  • Location where the time file is stored locally, on the z-Leaf computer.
• /xlsdirsrv dir
  • Location where the time file is copied when the experiment is finished. It prevents network traffic during the experiment.
• /counttriggers control_register,bit_to_test
  • Instructs z-Leaf to read the parallel port and record triggers from external hardware (i.e. fMRI
    scanner).

Input layouts

Integer number

1

Text (predefined)

!text: 1="one"; 2="two"; 3="three";

Radio

!radio: 1="one; 2=two"; 3="three";

Radioline

!radioline: 1="one"; 3="three";3;

Radiosequence

!radiosequence: 1="one; 2=two"; 3="three";

Slider

!slider: 1="one"; 3="three";3;

Scrollbar

!scrollbar: 1="one"; 3="three";3;

Checkbox

!checkbox: 1="one; 2=two"; 3="three";

Button

!button: 1="one; 2=two"; 3="three";

!string

Important functions

Scope operator

The scope operator : defines which variables are used to compute function's outcomes.

Take the following example form the manual

C = sum( A * B);
D = sum( :A * B);
E = sum( :A * :B);

A	B	C = sum( A * B )	D = sum( :A * B )	E = sum( :A * :B )
2	5	10 + 48 + 56 = 114	10 + 24 + 14= 48	10 + 10 + 10 = 30
4	12	10 + 48 + 56 = 114	20 + 48 + 28 = 96	48 + 48 + 48 = 144
8	7	10 + 48 + 56 = 114	40 + 96 + 56 = 192	56 + 56 + 56 = 168

This is an example taken from the manual (page 27)

A	V
1	3
4	6

B	V
7	8
10	11
13	14

This is the zTree code

X1= sum(V);
X2= tb.sum(V);
X3= tb.sum(:V);
X4= sum(:V);
X5= tb.sum(:V);
X6= sum( product (V) );
X7= sum( product (:V) );
X8= sum( product (::V) );
X9= tb.sum( product (V) );

These are the results

A	V	X1		X2		X3		X4		X6		X7		X8		X9
1	3	9	$3+6$	33	$8+11+14$	9	$3+3+3$	6	$3+3$	36	$3*6+6*3$	45	$3*3+6*6$	18	$3*3*3$	3696	$8*11*14$+$8*11*14$+$8*11*14$
4	6	9	$6+3$	33	$8+11+14$	18	$6+6+6$	12	$6+6$	36	$6*3+3*6$	45	$6*6+3*3$	72	$6*6*6$	3696	$8*11*14+8*11*14+8*11*14$

The scope operator allows also to specify the level to which we access one variable when functions are carried out in nested tables.

Take the following example: the variable $v$ is present in table $t_A$, in table $t_B$ and in table $t_C$.

Assume that the following operation is conducted in table $t_A$.

$X=\underbrace{v}_{t_A} +t_B.sum(\underbrace{v}_{t_B} * \underbrace{:v}_{t_A} + t_C.sum(\underbrace{v}_{t_C} * \underbrace{:v}_{t_B} * \underbrace{::v}_{t_A} ))$

The equation shows the "scoped" variables