REPORT ON THE REVIEW OF ENUT-94 S SAMPLE AND METHODOLOGY FOR THE CALCULATION OF ITS ADJUSTMENT FACTORS. Alfredo Aliaga

Transcripción

1 REPORT ON THE REVIEW OF ENUT-94 S SAMPLE AND METHODOLOGY FOR THE CALCULATION OF ITS ADJUSTMENT FACTORS Introduction By Alfredo Aliaga The present document presents a detailed revision of 1994 National Time-Use Survey (ENUT-94) sample s design carried out by ONE and INSTRAW. 1. The suggested design is described as a multistage, probabilistic, by conglomerates, stratified and proportional sample. 2. A listing of census segments established by the last National Population and Housing Census (1993) constitutes the sampling framework. 3. This survey covers the totality of the national territory of Dominican Republic. 4. Even when it has been stated that this sample is distributed proportionally to its population size, in fact we are dealing with a sample that approximates a proportional distribution. This can be observed in the presented Chart 2. See, in particular, the representation of the National District, which is larger in the sample compared to the census. 5. The sample s size is about 1500 households. Even when the size of the sample enables a variety of analysis, greater levels or domains of desegregation in order to make an analysis of data with a higher level of confidence, are not clearly established. According to the number of segments selected, it can be stated that these greater levels of desegregation correspond to the total of the country, to the residence area and the nine established strata (with a minimum of 41 excepting stratum rest ). 6. The segment framework was stratified in nine strata. National District constitutes a separated stratum and the rest of the areas of the country have been stratified in eight strata according to the following indicator: use of land. In total, there are 9 strata in the country. 7. On a first stage, sample s selection consists of a selection of areas for every stratum. Those areas that are larger than the area average entered the sample with certainty, with a probability of 1. A sample of the rest of areas was done. On a second stage, the supervision areas were selected, and finally the number of segments was selected. 8. In the initial document of sample s design it was stated that every selected segment should be updated in the field in order to obtain the current composition of

2 households and finally, achieve a selection of two households per segment. We regret that this process was carried out only in a few segments, remaining unknown for which segments this was done, and which were the results. 9. It is evident the lack of information of many sample s design parameters (such as the probability of area selection, etc.) and of implementation process records (apparently a correct classification of each case by rural/urban segment can not be obtained). 10. For every combination of strata and residence area, the ideal would have been to have the following parameters: a. Probability of area selection b. Probability of census area selection c. Probability of census segment selection d. Probability of household selection 11. The theoretic weight based on the sample s design would have been the inverse of the product of these four probabilities detailed in point 10. When this information was asked in diverse opportunities to Gisela Quiteiro, in order to calculate these parameters, the author could not obtain this information. After waiting and due to the fact that these parameters were not available, it was necessary to adopt an approximate solution. Apparently, the implementation of the sampling also lacks of necessary documentation, due to the fact that we do not count with explicit detail of the household updating process. This situation became much more complicated when a crossed table of complete (interviewed) cases per segment and residence area was asked in order to establish a better approximation of household selection probability for each segment. 12. The response to all this irregular situation in a study like ENUT-94 in Dominican Republic (supposing that census segments are quite alike in size inside every residence area) was the following: a. For every combination of strata and residence area (urban/rural) the final sample of census segments was considered as a random sample of simple segments of approximately same size. b. From the available documentation it was deduced that the average size of each urban segment was of 43 households and an average of 32 households for every rural segment. 13. Under these premises, for every combination of strata and residence area, the total probability of segment is expressed as the resultant value from the division of the number of segments selected in the sample by the total number of segments in the framework.

3 Inside the segment, the probability of household selection was 2 divided 43 for each urban segment and 2 divided 32 for every rural segment. 14. Finally, the approximate weight based on the sample s design used in ENUT-94 was calculated as the inverse of the product of the two last values (12 and 13). 15. These values of approximate weight based on the sample s design were adjusted by the household level of non-response for every stratum and residence area. 16. With the present document, two documents of Excel format are attached in order to follow the process that has been described in the precedent steps.

4 CHART SURVEY'S SEGMENTS FRAMEWORK Number of census Average of Number of urban Average of Number of Average of STRATA segments segments per segments urban rural rural stratum segments segments segments NATIONAL DISTRICT VEGETABLES AND GROCERIES SUGAR CANE COFFEE AND CACAO LIVESTOCK BANANAS AND ALIKE GRAINS TOBACCO REST TOTAL

5 CHART2. SAMPLE'S DISTRIBUTION Number of Average of Average of STRATA segments segments census in the sample in the sample segments NATIONAL DISTRICT VEGETABLES AND GROCERIES SUGAR CANE COFFEE AND CACAO LIVESTOCK BANANAS AND ALIKE GRAINS TOBACCO REST TOTAL

6 Chart 3. VALUE OF ADJUSTEMENT FACTORS FOR THE ENUT-94 SAMPLE Area Weight per Selected Complete Gross weight Expanded Weight STRATA approximate households housholds expansion households design (interviewed) standard NATIONAL DISTRICT Urban Rural VEGETABLES AND GROCERIES Urban Rural SUGAR CANE Urban Rural COFFEE AND CACAO Urban Rural LIVESTOCK Urban Rural BANANAS AND ALIKE Urban Rural GRAINS Urban Rural TOBACCO Urban Rural REST Urban Rural TOTAL

7 ANNEX 1: STRATA ESTRATA/AREAS URBAN ZONE RURAL ZONE URBAN ZONE RURAL ZONE ALFREDO SEGMENTS ALFREDO SEGMENTS SEGMENTS SEGMENTS TOTAL NATIONAL DISTRICT VEGETABLES AND GROCERIES Constanza Jarabacoa Azua Estebanía Las Charcas Bani Ocoa Nizao Palenque Rancho Arriba 8 36 Fundación (Peravia) Matanzas SUGAR CANE Sabana Grande de Boya San Pedro de Macorís Ramon Santana La Romana Puerto Plata Ing. Consuelo Ingenio Quisqueya Cevicos Yaguate Guaymate COFFEE AND CACAO

8 Tenares Peralta El Cercado Paraiso Enriquillo Polo La Descubierta Villa Jaragua San Jose de las Matas Los Hidalgos La Ciénaga 0 64 Hostos Poster Río Esperalvillo José Contreras Los Ríos Janico Pedro García Gaspar Hernández Guananico Altamira Restauración San Cristobal Villa Altagracia Cambita Los Cacaos Yamasa Miches Imbert LIVESTOCK Monte Plata Higuey Hato Mayor El Seibo Dajabón Partido

9 Montecristi Jamao al norte 9 45 Sosúa Las Salinas 22 7 Pedernales Oviedo Maimón Piedra Blanca Sabana Iglesisa 0 78 El Pino Las Yayas de Viajama Otra Banda Don Juan Duvergé Mella Las Matas de Farfán Pedro Santana 6 75 Bánica Río San Juan Cabrera BANANAS AND ALIKE Villa Tapia Barahona Cabral Cristóbal Galvan Tamayo Vicente Noble Tamboril Licey al Medio Moca Cayetano Germosen Mao Monción Pepillo Salcedo Bayaguana

10 El Valle La Vega El Peñon Fundación (Barahona) Ubilla Sabana Yegua Pueblo Viejo 0 84 San Victor GRAINS Esperanza San Ignacio de Sabaneta Los Almacigos Loma de Cabrera Las Matas de Santa Cruz Villa Vasquez Guayubin Castañuela Luperon San Francisco de Macoris Pimentel Guayabal Castillo Arenoso Cotui Fantino Las Guaranas Nagua 3 6 San Juan Juan de Herrera Comendador (Elias Piña) El Llano San José de los Llanos San Rafael del Yuma Nisibón Sabana de la Mar Hondo Valle 20 63

11 Bohechío Padre Las Casas Jima Abajo Bonao Sabana Larga Vallejuelo El Factor Juan Santiago 9 32 La Mata TOBACCO Tabara Arriba Santiago Villa Bisono (Navarrete) La Isabela Laguna Salada Villa Gonzalez REST Samana Neyba Sanchez Villa Riva Jimaní Bajos de Haina Nigua Las Terrenas Salcedo La Cueva Sabana Buey 10 2