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Table 1 The calculation of participation rates according to the American Association of Public Opinion Research, AAPOR [23]

From: Participation rates, response bias and response behaviours in the community survey of the Swiss Spinal Cord Injury Cohort Study (SwiSCI)

 

Abbreviations/Calculation

Explanation

Response status

  

 Participation

I

Subjects who participated in a module

 Refusal

R

Subjects who refused to participate in a module

 No contact

NC

Subjects who received the postal invitation but could not be personally contacted due to unavailability of telephone number or unsuccessful telephone calls (10 failed attempts); deceased or moved away from Switzerland after selection but before contact could be made

 Not eligible

NE

Subjects who were excluded after first contact as they did not meet inclusion criteria defined in the study protocol (deceased or moved away from Switzerland before the date of the invitational letter; insufficient language skills in German, French or Italian; other medical diagnoses than defined in the study protocol; poor cognitive health status; non-existent or wrong contact informationa)

 Eligible

E = I + R + NC

Subjects eligible for the survey

Participation rates

  

 Absolute cooperation rate

[I/(I + R)]*100

% of subjects who participated of those who were contacted in a specific module

 Cumulative cooperation rate

[I/(I + Rtot)]*100

% of subjects who participated of those who were contacted up to a specific module

 Absolute contact rate

[(I + R)/(I + R + NC)]*100

% of eligible subjects who could be contacted in a specific module

 Cumulative contact rate

[(I + Rtot)/(I + Rtot + NCtot)]*100

% of eligible subjects who could be contacted up to a specific module

 Absolute response rateb

[I/(I + R + NC)]*100

% of subjects who participated of the total number of eligible subjects in a specific module

 Cumulative response rate

[I/(I + Rtot + NCtot)]*100

% of subjects who participated of the total number of eligible subjects up to a specific module

 Absolute attrition rate

[1- [I/(I + R + NC)]]*100

% of subjects who refused participation in a specific wave after participation in a former module

 Cumulative attrition rate

[1- (I/(I + Rtot + NCtot))]*100

% of all subjects who refused participation after participation in a former module

  1. aAccording to AAPOR’s definition, the category ‘non-existent or wrong contact information’ is grouped as ‘unknown if household/occupied household unit’ (UH), or ‘unknown, other’ (UO). For the 88 cases that never received the invitational letter, we carefully investigate their status with Swiss public authorities and could not detect their actual stay. We therefore assume that they are either deceased or moved away from Switzerland and categorized them as NE
  2. bAccording to AAPOR’s definition ‘Response Rate 5’ assuming that there are no eligible cases among the cases of unknown eligibility (see footnote a)
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BMC Medical Research Methodology

ISSN: 1471-2288

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