Langbein, Laura Irwin. <br/><br/>
Discovering whether programs work :  a guide to statistical methods for program evaluation / 
Laura Irwin Langbein. 
 - Santa Monica, Calif. :  Goodyear Pub. Co.,  c1980. 
 - viii, 184 p. :  ill. ;  23 cm. 
<br/><br/><label>ISBN: </label>0830222146 (pbk.) 
<br/><br/><label>LCCN: </label>79027878  
<br/><br/><label>LC Class. No.: </label>HA33 .L34 1980  / .L34 
<br/><br/><label>Dewey Class. No.: </label>361.6/07/2