id	author	title	date	pages	extension	mime	words	sentence	flesch	summary	cache	txt
crln-20644	Hawthorn, Margaret; Goettler, Elaine	Proportionate probability sampling	1993-06-01	3	.pdf	application/pdf	1653	80	67	The time frame and the com prehensibility of the questions w ere pretested using library student assistants. Survey needs As in many other libraries, questionnaires had b een h an d ed out at the library door during sample time periods, surveying some of those students w ho entered the library but obtaining no information on students w ho were n o t li­ brary users.	cache/crln-20644.pdf	txt/crln-20644.txt