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  <citation>
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      <IDNo>DDI_WLD_2020_CTIS_v01_M_WB</IDNo>
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      <producer abbr="DECDG" affiliation="World Bank Group" role="Documentation of the DDI">Data Development Group</producer>
      <prodDate date="2021-10-27">2021-10-27</prodDate>
      <software version="v5">NADA</software>
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      <version>Version 1 (October 2021)</version>
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  <citation>
    <titlStmt>
      <titl>COVID-19 Trends and Impact Survey (2020-Ongoing)</titl>
      <subTitl/>
      <altTitl>CTIS 2020</altTitl>
      <parTitl/>
      <IDNo>WLD_2020_CTIS_v01_M</IDNo>
    </titlStmt>
    <rspStmt>
      <AuthEnty affiliation="">Facebook Data for Good</AuthEnty>
      <AuthEnty affiliation="">Carnegie Mellon University</AuthEnty>
      <AuthEnty affiliation="">University of Maryland</AuthEnty>
    </rspStmt>
    <prodStmt>
      <copyright/>
      <software version="5.0" date="2021-11-05">NADA</software>
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      <serName/>
      <serInfo>Facebook partners with academic institutions to support COVID-19 research and to help inform public health decisions. The COVID-19 Trends and Impact Survey (CTIS) is designed to help researchers better monitor and forecast the spread of COVID-19. Facebook invites app users in the United States to take the survey collected by faculty at Carnegie Mellon University (CMU) Delphi Research Center and users in more than 200 countries and territories globally to take the survey collected by faculty at the University of Maryland (UMD) Joint Program in Survey Methodology (JPSM). Sampled users see the invitation at the top of their News Feed, but the surveys are collected off the Facebook app and the Facebook company does not collect or receive survey responses. UMD and CMU (“survey host universities”) each partnered with the broader public health community to design the survey. The survey includes questions about COVID-19 vaccine acceptance, barriers to getting a vaccine, symptoms, preventive behaviors, access to care, social distancing behavior, mental health issues, socio-demographic characteristics and financial constraints. This information may help health systems plan where resources are needed and potentially when, where, and how to reopen parts of society.  
 
CMU and UMD aggregate survey responses at a subnational level and then publish the data publicly in APIs -- one for the United States and one for the rest of the world. Microdata is also available to nonprofits and universities through Facebook’s Data for Good program.</serInfo>
    </serStmt>
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      <notes/>
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    <abstract>Facebook partners with academic institutions to support COVID-19 research and to help inform public health decisions. The COVID-19 Trends and Impact Survey (CTIS) is designed to help researchers better monitor and forecast the spread of COVID-19. Facebook invites app users in the United States to take the survey collected by faculty at Carnegie Mellon University (CMU) Delphi Research Center and users in more than 200 countries and territories globally to take the survey collected by faculty at the University of Maryland (UMD) Joint Program in Survey Methodology (JPSM). Sampled users see the invitation at the top of their News Feed, but the surveys are collected off the Facebook app and the Facebook company does not collect or receive survey responses. UMD and CMU (“survey host universities”) each partnered with the broader public health community to design the survey. The survey includes questions about COVID-19 vaccine acceptance, barriers to getting a vaccine, symptoms, preventive behaviors, access to care, social distancing behavior, mental health issues, socio-demographic characteristics and financial constraints.  This information may help health systems plan where resources are needed and potentially when, where, and how to reopen parts of society.  
 
CMU and UMD aggregate survey responses at a subnational level and then publish the data publicly in APIs -- one for the United States and one for the rest of the world. Microdata is also available to nonprofits and universities through Facebook’s Data for Good program.</abstract>
    <sumDscr>
      <collDate date="2020-04" event="start" cycle=""/>
      <collDate date="2021" event="end" cycle=""/>
      <nation abbr="AFG">Afghanistan</nation>
      <nation abbr="ALB">Albania</nation>
      <nation abbr="DZA">Algeria</nation>
      <nation abbr="AGO">Angola</nation>
      <nation abbr="ARG">Argentina</nation>
      <nation abbr="ARM">Armenia</nation>
      <nation abbr="AUS">Australia</nation>
      <nation abbr="AUT">Austria</nation>
      <nation abbr="AZE">Azerbaijan</nation>
      <nation abbr="BGD">Bangladesh</nation>
      <nation abbr="BLR">Belarus</nation>
      <nation abbr="BEL">Belgium</nation>
      <nation abbr="BEN">Benin</nation>
      <nation abbr="BOL">Bolivia</nation>
      <nation abbr="BIH">Bosnia and Herzegovina</nation>
      <nation abbr="BRA">Brazil</nation>
      <nation abbr="BGR">Bulgaria</nation>
      <nation abbr="BFA">Burkina Faso</nation>
      <nation abbr="KHM">Cambodia</nation>
      <nation abbr="CMR">Cameroon</nation>
      <nation abbr="CAN">Canada</nation>
      <nation abbr="CHL">Chile</nation>
      <nation abbr="COL">Colombia</nation>
      <nation abbr="CRI">Costa Rica</nation>
      <nation abbr="CIV">Côte d’Ivoire</nation>
      <nation abbr="HRV">Croatia</nation>
      <nation abbr="CZE">Czech Republic</nation>
      <nation abbr="DNK">Denmark</nation>
      <nation abbr="DOM">Dominican Republic</nation>
      <nation abbr="ECU">Ecuador</nation>
      <nation abbr="EGY">Egypt, Arab Rep.</nation>
      <nation abbr="SLV">El Salvador</nation>
      <nation abbr="ETH">Ethiopia</nation>
      <nation abbr="FIN">Finland</nation>
      <nation abbr="FRA">France</nation>
      <nation abbr="DEU">Germany</nation>
      <nation abbr="GHA">Ghana</nation>
      <nation abbr="GRC">Greece</nation>
      <nation abbr="GTM">Guatemala</nation>
      <nation abbr="HTI">Haiti</nation>
      <nation abbr="HND">Honduras</nation>
      <nation abbr="HKG">Hong Kong SAR, China</nation>
      <nation abbr="HUN">Hungary</nation>
      <nation abbr="IND">India</nation>
      <nation abbr="IDN">Indonesia</nation>
      <nation abbr="IRQ">Iraq</nation>
      <nation abbr="IRL">Ireland</nation>
      <nation abbr="ISR">Israel</nation>
      <nation abbr="ITA">Italy</nation>
      <nation abbr="JPN">Japan</nation>
      <nation abbr="JOR">Jordan</nation>
      <nation abbr="KAZ">Kazakhstan</nation>
      <nation abbr="KEN">Kenya</nation>
      <nation abbr="KOR">Korea, Rep.</nation>
      <nation abbr="KGZ">Kyrgyz Republic</nation>
      <nation abbr="LAO">Lao PDR</nation>
      <nation abbr="LBN">Lebanon</nation>
      <nation abbr="LBY">Libya</nation>
      <nation abbr="MDG">Madagascar</nation>
      <nation abbr="MYS">Malaysia</nation>
      <nation abbr="MLI">Mali</nation>
      <nation abbr="MRT">Mauritania</nation>
      <nation abbr="MEX">Mexico</nation>
      <nation abbr="MDA">Moldova</nation>
      <nation abbr="MAR">Morocco</nation>
      <nation abbr="MOZ">Mozambique</nation>
      <nation abbr="MMR">Myanmar</nation>
      <nation abbr="NPL">Nepal</nation>
      <nation abbr="NLD">Netherlands</nation>
      <nation abbr="NIC">Nicaragua</nation>
      <nation abbr="NGA">Nigeria</nation>
      <nation abbr="NOR">Norway</nation>
      <nation abbr="OMN">Oman</nation>
      <nation abbr="PAK">Pakistan</nation>
      <nation abbr="PAN">Panama</nation>
      <nation abbr="PRY">Paraguay</nation>
      <nation abbr="PER">Peru</nation>
      <nation abbr="PHL">Philippines</nation>
      <nation abbr="POL">Poland</nation>
      <nation abbr="PRT">Portugal</nation>
      <nation abbr="PRI">Puerto Rico</nation>
      <nation abbr="QAT">Qatar</nation>
      <nation abbr="ROU">Romania</nation>
      <nation abbr="RUS">Russian Federation</nation>
      <nation abbr="SAU">Saudi Arabia</nation>
      <nation abbr="SEN">Senegal</nation>
      <nation abbr="SRB">Serbia</nation>
      <nation abbr="SGP">Singapore</nation>
      <nation abbr="SVN">Slovenia</nation>
      <nation abbr="ZAF">South Africa</nation>
      <nation abbr="ESP">Spain</nation>
      <nation abbr="LKA">Sri Lanka</nation>
      <nation abbr="SWE">Sweden</nation>
      <nation abbr="CHE">Switzerland</nation>
      <nation abbr="TZA">Tanzania</nation>
      <nation abbr="TWN">Taiwan, China</nation>
      <nation abbr="THA">Thailand</nation>
      <nation abbr="TUN">Tunisia</nation>
      <nation abbr="TUR">Turkey</nation>
      <nation abbr="UKR">Ukraine</nation>
      <nation abbr="ARE">United Arab Emirates</nation>
      <nation abbr="GBR">United Kingdom</nation>
      <nation abbr="USA">United States</nation>
      <nation abbr="URY">Uruguay</nation>
      <nation abbr="UZB">Uzbekistan</nation>
      <nation abbr="VEN">Venezuela, RB</nation>
      <nation abbr="VNM">Vietnam</nation>
      <nation abbr="WBG">West Bank and Gaza</nation>
      <nation abbr="YEM">Yemen, Rep.</nation>
      <geogCover>The surveys are fielded daily in over 200 countries and territories.</geogCover>
      <geogUnit/>
      <anlyUnit>- Public Aggregate Data: Subnational levels
- Microdata through Facebook Data for Good program: Individual level</anlyUnit>
      <universe>The survey was fielded to active Facebook users ages 18 and above.</universe>
      <dataKind>Sample survey data [ssd]</dataKind>
    </sumDscr>
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     In standardsCompliance list all specific standards complied with during the execution of this 
     study. Note the standard name and producer and how the study complied with the standard. 
     Enter any additional quality statements in otherQualityStatements.
     
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        <standard>
          <standardName/>
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        <complianceDescription/>
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      <otherQualityStatement/>
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    <notes>CTIS includes questions about COVID-19 vaccine acceptance, barriers to getting a vaccine, symptoms, preventive behaviors, access to care, social distancing behavior, mental health issues, socio-demographic characteristics and financial constraints. The survey instruments are owned by the survey host universities and are available, along with their translations, with the data. 

Survey Instruments &amp; Documentation:
- UMD Global Survey Instrument
- CMU US Survey Instruments
 
Qualtrics Previews
- Global survey questionnaire from UMD
- US survey questionnaire from CMU</notes>
    <!-- exPostEvaluation ddi2.5
      Use this section to describe evaluation procedures not address in data evaluation processes. 
      These may include issues such as timing of the study, sequencing issues, cost/budget issues, 
      relevance, instituional or legal arrangments etc. of the study. 
      
      The completionDate attribute holds the date the evaluation was completed. 
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      the use of a controlled vocabulary.
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      <outcomes/>
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  <method>
    <dataColl>
      <timeMeth/>
      <!-- collectorTraining - DDI2.5
        
        Collector Training

        Describes the training provided to data collectors including internviewer training, process testing, 
        compliance with standards etc. This is repeatable for language and to capture different aspects of the 
        training process. The type attribute allows specification of the type of training being described.
        
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      <collectorTraining type=""/>
      <frequenc/>
      <sampProc>CMU and UMD design, collect, and analyze the survey data. Facebook provides assistance with questionnaire translation, survey sampling and recruitment, and statistical bias correction. Facebook invites a new sample of adult users on the Facebook App to take the survey each day. These users see an invitation at the top of their Facebook News Feed to an optional, off Facebook survey. The sampled users can then choose whether or not to consent to the survey. If they consent, they are redirected to a Qualtrics survey hosted by UMD or CMU. The surveys are daily repeated cross-sections. Sampled users may be invited to take the survey again in either a few weeks or months, depending on the density of their area. 
 
We stratify the sample using administrative boundaries within countries and territories to provide geographic coverage. We are constantly working with the survey host universities to optimize the sampling design, including incorporating adaptive sampling, which could improve statistical power for local area estimates in priority areas as the pandemic progresses. 
 
The responses of sampled users who participate more than once will not be linked longitudinally. In order to enable an agile public health response, we aim to provide data that can detect either outbreaks or successful containment over time rather than cumulative or overall prevalence alone.</sampProc>
      <sampleFrame>
        <sampleFrameName/>
        <custodian/>
        <universe/>
        <frameUnit isPrimary="">
          <unitType numberOfUnits=""/>
        </frameUnit>
        <updateProcedure/>
      </sampleFrame>
      <deviat/>
      <collMode>Internet [int]</collMode>
      <resInstru>CTIS includes questions about COVID-19 vaccine acceptance, barriers to getting a vaccine, symptoms, preventive behaviors, access to care, social distancing behavior, mental health issues, socio-demographic characteristics and financial constraints. The survey instruments are owned by the survey host universities and are available, along with their translations, with the data at the following links: 

https://gisumd.github.io/COVID-19-API-Documentation/docs/survey_instruments.html
https://cmu-delphi.github.io/delphi-epidata/symptom-survey/coding.html
https://umdsurvey.umd.edu/jfe/preview/SV_2mWYHEMq5ZoUBNj?Q_CHL=preview&amp;Q_JFE=qdg
https://cmu.ca1.qualtrics.com/jfe/preview/SV_cT2ri3tFp2dhJGZ?Q_SurveyVersionID=current&amp;Q_CHL=preview</resInstru>
      <!-- instrumentDevelopment - DDI2.5             
        Describe any development work on the data collection instrument. Type attribute allows for the optional use of a defined development type with or without use of a controlled vocabulary.
        -->
      <instrumentDevelopment type=""/>
      <collSitu>In partnership with CMU and UMD, people on Facebook are invited to participate in surveys that ask about COVID-19 vaccine acceptance, barriers to getting a vaccine, symptoms, preventive behaviors, access to care, social distancing behavior, mental health issues, socio-demographic characteristics and financial constraints. 
 
To ensure that the survey sample more accurately reflects the characteristics of the population represented in the data, Facebook shares with CMU and UMD a random ID number and a single statistic, known as a weight value, that doesn’t identify a survey respondent but helps correct for survey sample bias. Facebook also shares the participant's language preference with these partners. 
 
Facebook does not receive any survey responses to do this bias correction. Instead, UMD and CMU send Facebook the Random ID number for the users who completed the survey. Facebook only has access to public, aggregated survey data provided by the universities.</collSitu>
      <actMin/>
      <ConOps/>
      <weight/>
      <cleanOps/>
    </dataColl>
    <notes/>
    <anlyInfo>
      <respRate>Response rates to online surveys vary widely depending on a number of factors including survey length, region, strength of the relationship with invitees, incentive mechanisms, invite copy, interest of respondents in the topic and survey design.</respRate>
      <EstSmpErr>Any survey data is prone to several forms of error and biases that need to be considered to understand how closely the results reflect the intended population. Sampling error is a natural characteristic of every survey based on samples and reflects the uncertainty in any survey result that is attributable to the fact that not the whole population is surveyed.
 
Facebook provides analytic weights that adjust for non-response and coverage biases. By non-response bias, Facebook means that some sampled users are more likely to respond to the survey than others. To adjust for this, Facebook calculates the inverse probability that sampled users complete the survey using their self-reported age and gender as well as other characteristics we know correlate with non-response. They then use these inverse probabilities to create weights for responses, after which the survey sample reflects the active adult user population on the Facebook app. 
 
By coverage bias, Facebook means that not everyone in every country has a Facebook app account or uses their account regularly. To adjust for this, Facebook adjusts the weights created in the first step even further so that the distribution of age, gender, and administrative region of residence in the survey sample reflects that of the general population. Making adjustments using the weights ensures that the sample more accurately reflects the characteristics of the target population represented. 
 
The weights will be available for the United States as well as 114 other countries and territories globally where we are able to generate high-quality weights. The current set of weighted countries and territories are listed on the next page. The set of countries and territories for which weights are available will be revised over the course of data collection as Facebook and the survey host universities evaluate sample coverage within each country. For more details about the weighting methodology and the general population benchmarks used, please see this weighting documentation:  https://arxiv.org/abs/2009.14675</EstSmpErr>
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  <dataAccs>
    <setAvail>
      <accsPlac URI="https://dataforgood.facebook.com/dfg/tools/covid-19-trends-and-impact-survey">Facebook Data for Good</accsPlac>
      <origArch>Facebook Data for Good
https://dataforgood.facebook.com/dfg/tools/covid-19-trends-and-impact-survey</origArch>
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      <notes/>
    </setAvail>
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      <citReq>Use of the dataset must be acknowledged using a citation which would include:
- the Identification of the Primary Investigator
- the title of the survey (including country, acronym and year of implementation)
- the survey reference number
- the source and date of download

Example:

Facebook, Carnegie Mellon University, and University of Maryland. World - Facebook: COVID-19 Trends and Impact Survey 2020-Ongoing. Ref: WLD_2020_CTIS_v01_M. Downloaded from [url] on [date].</citReq>
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      <disclaimer/>
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    <notes/>
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