of the urbanized areas using the ordered 

 lists and 1950 census data on the number of 

 occupied dwelling units or households found 

 In each census tract, block or enumeration 

 district. These strata, seventy in number 

 for each urbanized area, were constructed 

 to contain approximately the same nvmiber 

 of households in each. 



Each of the seventy strata was then 

 divided into a number of «™»n area seg- 

 ments having boundaries which could easily 

 be identified In the field by the inter- 

 viewers. Each such area segment conteiined 

 one or more clusters of households or sam- 

 pling units. The number of sampling xinlts 

 or Interviewer work loads assigned to each 

 area segment was based on data available on 

 the nxmiber of occupied dwelling xmits lo- 

 cated within these segment boundaries. 

 These data were obt«d.ned from a variety of 

 sources including 1950 block statistics, 

 1950 enumeration district statistics, state 

 highway maps, etc. 



The geographic strata in each city 

 were all constructed to contain the same 

 number of sampling units with the exception 

 of Detroit. In the cenla-al city portion of 

 Detroit, the area strata for the tracts in 

 the white zone (that is, the tracts with at 

 least 90 percent of their 195O dwelling 

 vinits occupied by white families) were con- 

 structed to contain twice as many sampling 

 units as the remaining area strata estab- 

 lished for the Detroit urbemized area 

 sample. Initially, two sampling units were 

 selected with equal probability and without 

 replacement from each of the geographic 

 strata, yielding a sample total of lUO 

 sampling units for each urbemlzed area. 



The sample selection was accomplished 

 by choosing two random numbers for each 

 stratum between one and the total number of 

 sampling units in the stratum. Thus, the 

 sampling rate was the same for aill geo- 

 graphic strata within a city with the ex- 

 ception of those comprising the white zone 

 in Detroit referred to above. Since these 

 strata contained twice as msmy sampling 

 units as the remaining geographic strata 

 in Detroit they were sampled at one -half 

 the rate of the remaining strata in that 

 urbanized area. The disproportionate sam- 

 pling in Detroit was deemed necessary to 

 yield sufficient interviews with non-^rtilte 

 families for separate tabulation. 



The number of strata and sampling 

 units for the central cities and the re- 

 maining portions of the three urbemlzed 

 £ureas axe shown in the following table: 



Appendix Table 1 



WJMBER OF STRATA AND SAMPLING UNITS OF 



URBANIZED AREAS INCLUDED IN THE 



MOTIVATION SURVEY 



The decision to include a sample of 

 non-white households in Orangeburg, South 

 Carolina was made after the sample for the 

 three principal urbanized areas was de- 

 signed and selected. The expected sample 

 size in each of the three urbanized sureas 

 was then reduced frcan QkO households to 

 725 households in order to shift a portion 

 of the field budget to the survey to be 

 conducted in Orangeburg Cotinty. Rather 

 than design euad select a new sample in 

 each of the three urbanized areas, twenty 

 sampling units in Birmingham, thirteen in 

 Boston, 6uid twenty-eight in Detroit were 

 discarded at random with a condition that 

 no more than one sampling unit would be 

 discarded fran any one stratimi. 



Strict field procedures were employed 

 to determine the eligible households 

 associated with the selected sampling units 

 in an unbiased memner. The interviewers 

 were required to list the occupied dwelling 

 units in each area segment containing a 

 selected sampling unit in advance of the 

 interviewing. The listings showed addresses 

 and other necessary identification for all 

 dwelling units located within the boundaries 

 of each area segment. The enumerators were 

 provided with maps showing these boundaries, 

 as well as the starting point and direction 



^9 



