Seat strap SURVEY DESIGN IN ILLINOIS

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´╗┐Seat strap SURVEY DESIGN IN ILLINOIS Mehdi Nassirpour, Ph.D. Illinois Department of Transportation

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OBJECTIVE OF THE SURVEY To plan a multi-organize bunch irregular example keeping in mind the end goal to assess the statewide seat strap utilization rate in Illinois. Division of Traffic Safety at IDOT

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SAMPLE DESIGN SUMMARY IN ILLINOIS City of Chicago 77 Communities Cook C No Chicago 30 Townships Other Counties 101 Counties Stage 1 Urban Rural Census Tracts Census Tracts Census Tracts Census Tracts Stage 2 Road Type Road Type Stage 3 Road Type Road Type HVR LVR HVR LVR HVR LVR

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ALLOCATION OF SAMPLE SITES Total Sample (258 Sites Cook County (92 Sites) 12 Counties (166 Sites) City of Chicago (51 Sites) Cook County No Chicago (41 Sites)

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STAGE 1 - PSU SELECTION Sampling Units - 20 PSU 5 Community Areas in the City of Chicago 3Townships in Cook County 11 Counties (DuPage County was chosen twice) 4 out of 11 districts were country regions. 47 regions were wiped out because of a little number of VMTs and populace. 54 areas contains around 90 percent of VMT and populace Selection - Probability Proportional to Vehicle Miles of Travel and Population. Determination is deliberate (1/Ns) After Random Start

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SAFETY BELT LOCATIONS IN IL MCHENRY COUNTY LOCATIONS (6) LAKE COUNTY LOCATIONS (31) KANE COUNTY LOCATIONS (14) WILL COUNTY LOCATIONS (18) CHICAGO LOCATIONS (49) COOK COUNTY LOCATIONS (40) DUPAGE COUNTY LOCATIONS (42) CHAMPAIGN COUNTY LOCATIONS (9) ROCK ISLAND CO. Areas (7) PEORIA COUNTY LOCATIONS (9) MONTGOMERGY COUNTY LOCATIONS (2) ST. CLAIR COUNTY LOCATIONS (14) Division of Traffic Safety at IDOT

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STAGE 2 - CENSUS TRACT SELECTION Census Tracts An aggregate of 96 statistics tracts (10-12 percent of aggregate tracts) inside those chose provinces were chosen arbitrarily. Determination - Probability Proportional to Population. Choice is efficient (1/Ns). After Random Start Division of Traffic Safety at IDOT

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STAGE 3 - ROAD TYPE SELECTION Road Type All streets (Interstates, expressways, US/IL roadways, and private boulevards) inside chose tracts were distinguished utilizing tract maps. All Interstates and IL/US roadways inside these tracts were chosen with sureness and different streets were chosen haphazardly. Division of Traffic Safety at IDOT

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PROCEDURE USED TO ASSIGN OBSERVATION SITES TO OBSERVATION TIME PERIOD Selected streets haphazardly doled out to time of day and day of week. To minimize travel time and separation required to direct the perceptions, the inspected destinations were assembled into 29 geographic groups , with every bunch containing about somewhere around 6 and 12 street locales. Every group is haphazardly (without substitution) relegated to a day of the week. Every day was isolated into eight one-hour eras between 7:00am to 6:30pm when the light was sufficient for perception . Division of Traffic Safety at IDOT

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Weighting Procedures W ctr = 1/P ctr P ctr = P c . P t/c . P r/ct c identifies a specimen of region t identifies an example of tract r identifies a specimen of street site P c probability of selecting district c P t/c probability of selecting tract t inside selected province c P r/ct probability of selecting street r, restrictive to the tract and area Division of Traffic Safety at IDOT

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FORMULA FOR ESTIMATING SAFETY BELT USAGE RATE R = Safety belt utilization rate W ctr = weight connected with street r in tract t in region c; X ctr = number of wellbeing belted front seat tenants of passenger autos and get trucks watched in county c , tract t , and street site r ; and Y ctr = number of front seat inhabitants saw in county c , tract t , and street site r . Division of Traffic Safety at IDOT

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FORMULA FOR ESTIMATING SAFETY BELT USAGE RATE F ctr = change for paths not saw in street site r, tract t in district c ; L ctr = add up to number of paths in street site r , tract t in province c ; and O ctr = add up to number of watched paths in street site r inside tract t in region c .

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VARIANCE ESTIMATION Estimated seat strap utilization rate is liable to examining mistake since a little number of front seat tenants were watched. These testing mistakes are communicated as coefficients of variety (relative blunder), that are the proportions of the relative standard blunders of assessments to the evaluations themselves. . Division of Traffic Safety at IDOT

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VARIANCE ESTIMATION PACKAGE PC CARP from the Iowa state University was utilized to evaluate the coefficient of variety for a proportion from a stratified group test. PC CARP is a menu driven program and is intended to develop evaluations and standard blunders for aggregates, implies, proportions, contrasts of proportions, and substances in two-route tables for multi-arrange stratified specimen. The fundamental contribution for the program is the stratum distinguishing proof, bunch ID, weight, and information vector for an arrangement of perceptions. . Division of Traffic Safety at IDOT

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VARIANCE ESTIMATION FORMULA (Y ijkl , X ijkl , Y ijk2 , X ijk2 , ...., Y ijkp , X ijkp ) where i= 1, 2, ....l j = 1, 2, ...,nj; k = 1, 2,...., mij; i is the stratum distinguishing proof, j is the bunch ID, k is the component inside group recognizable proof. The above vector is utilized as a part of the examination and estimator is .

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Safety Belt Usage Rates in Illinois, July 2003

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PUBLIC OPINION SURVEY OF "Snap IT OR TICKET" CAMPAIGN Mehdi Nassirpour Illinois Department of Transportation

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SURVEY RESEARCH CENTER In the Spring of 2003, the Illinois Department of Transportation contracted with the Survey Research Office at the University of Illinois at Springfield to direct two phone overviews. Two of the reviews were led previously, then after the fact a noteworthy safety belt activity (that included both media and implementation related exercises that happened amid a day and age encompassing Memorial Day Weekend, 2003. Meeting for the "pre-test" (before) review was led from April 25 to May 4, 2003, and meeting for the "post-test" (after) study was led from June 3 to 18, 2003. Division of Traffic Safety at IDOT

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OBJECTIVES To gather statewide information and data on open mindfulness and acknowledgment of the seat strap program amid the "Snap it or Ticket" program in Illinois at five focuses (some time recently, amid and after the battle). To portray drivers' sentiments on seat strap utilize and related issues, controlling for demographics amid the benchmark and follow-up information gathering periods. To recognize key variables to help the Division of Traffic Safety to gauge viability of the generally speaking "Snap it or Ticket" program and administrations in Illinois utilizing the pre and post approach . Division of Traffic Safety at IDOT

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CLICK IT OR TICKET CAMPAIGN " Click It or Ticket " is a high perceivability, enormous requirement exertion intended to recognize violators of Illinois activity laws with exceptional accentuation on tenant insurance. An extraordinary open data and training effort was run simultaneously with the requirement rush to educate the motoring open of the advantages of safety belt utilize and of issuing tickets for safety belt infringement. The objective of the "Snap It or Ticket" crusade is to spare lives and lessen wounds coming about because of engine vehicle crashes by expanding the seat strap utilization rate in Illinois by no less than 3-5 rate focuses . Division of Traffic Safety at IDOT

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MEDIA/ENFORCEMENT Several media occasions were held all through the state on April 28, 2003 declaring the requirement endeavors made arrangements for May 15 - June 1, 2003. A sum of 421 nearby offices and in addition Illinois State Police and Secretary of State Police organizations took an interest in the authorization battle and issued 46,434 references. More than 26,085 worker hours were directed an assortment of authorization endeavors. Division of Traffic Safety at IDOT

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STRATIFIED RANDOM SAMPLE Total Sample Downstate Chicago Metro City of Chicago North and Central Illinois Chicago Area Suburbs Southern Illinois Division of Traffic Safety at IDOT

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SAMPLING METHODOLOGY Random examples of phone numbers were bought for each of the four stratification ranges (City of Chicago, Chicago Suburban Counties, North/Central Illinois, and Southern Illinois). Every phone number in the examples was known as a most extreme of six times, at varying times of the week and day. Inside family units, questioners requested the most youthful authorized driver 75 percent of the time, on the grounds that prior experience demonstrated that we under-speak to more youthful drivers. In the other 25 percent of the time, questioners requested an authorized driver who was male/female (changing indiscriminately) and who had the following birthday. Substitutions were acknowledged if that assigned family unit part was not accessible. Division of Traffic Safety at IDOT

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DISTRIBUTION OF THE SAMPLES (Pre=560 and Post=623) Division of Traffic Safety at IDOT

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SAMPLING ERROR The examining mistake for the statewide results is under +/ - 5 percent (at the 95th certainty level) for both the pre-test study (+/ - 4.2%) and the post-test study (+/ - 4.0%). The mistake for subgroups is, obviously, bigger. Division of Traffic Safety at IDOT

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SAMPLE WEIGHTS The statewide results for both overviews have been weighted to touch base at a legitimate dissemination by area and by sexual orientation . Division of Traffic Safety at IDOT

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DEMOGRAPHIC CHARACTERISTICS OF PRE AND POST SAMPLES The biggest contrast seems, by all accounts, to be that for business status, where the post-test study has less full-time workers (37%, contrasted with 45% in the pre-test). The post-test respondents are additionally to some degree more youthful and have to some degree more minority respondents. The post test likewise has to some degree a greater number of families with more than one individual of driving age in the hou

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