***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    ***EXAMPLES*** 
    Input: Background Postal question naires are widely used to collect data in healthcare research but a poor response rate may reduce the validity and reliability of results . There was a lack of evidence available relating to use of a monetary incentive to improve the response rate in the healthcare setting . Methods The MRC ORACLE Children Study is assessing the health and development of nearly 9000 seven year old children whose mothers ' joined the MRC ORACLE Trial . We carried out a r and omised controlled trial of inclusion of monetary incentive ( five pound voucher redeemable at many high street stores ) with the reminder question naire to parents . This trial took place between April 2002 and November 2003 . When the parents were sent the reminder question naire about their child 's health and development they were r and omly assigned by concealed computer-generated allocation stratified by week of birthday to receive a five pound voucher or no incentive . The population were 722 non-responders to the initial mailing of a 12-page question naire . Main outcome measures : Difference in response rate between the two groups . Results Inclusion of the voucher with the reminder question naire result ed in a 11.7%(95 % CI 4.7 % to 18.6 % ) improvement in the response rate between the two groups . Conclusion This improvement in response rate and hence the validity and reliability of results obtained appears to be justified ethically and financially A motivational orientation intervention design ed to improve  parenting  program retention was field tested versus st and ard orientation across two parenting programs , Parent — Child Interaction Therapy ( PCIT ) and a st and ard didactic parent training group . Both interventions were implemented within a frontline child welfare parenting center by center staff . Participants had an average of six prior child welfare referrals , primarily for neglect . A double-r and omized design was used to test main and interaction effects . The motivational intervention improved retention only when combined with PCIT ( cumulative survival = 85 % vs. around 61 % for the three other design cells ) . Benefits were robust across demographic characteristics and participation barriers but were concentrated among participants whose initial level of motivation was low to moderate . There were negative effects for participants with relatively high initial motivation . The findings suggest that using a motivational intervention combined with PCIT can improve retention when used selectively with relatively low to moderately motivated child welfare clients Background Sending a monetary incentive with postal question naires has been found to improve the proportion of responders , in research in non-healthcare setting s. However , there is little research on use of incentives to improve follow-up rates in clinical trials , and existing studies are inconclusive . We conducted a r and omised trial among participants in the Managing Injuries of the Neck Trial ( MINT ) to investigate the effects on the proportion of question naires returned and overall non-response of sending a £ 5 gift voucher with a follow-up question naire . Methods Participants in MINT were r and omised to receive either : ( a ) a £ 5 gift voucher ( incentive group ) or ( b ) no gift voucher ( no incentive group ) , with their 4 month or 8 month follow-up question naire . We recorded , for each group , the number of question naires returned , the number returned without any chasing from the study office , the overall number of non-responders ( after all chasing efforts by the study office ) , and the costs of following up each group . Results 2144 participants were r and omised , 1070 to the incentive group and 1074 to the no incentive group .  The proportion of question naires returned ( RR 1.10 ( 95 % CI 1.05 , 1.16 ) ) and the proportion returned without chasing ( RR 1.14 ( 95 % CI 1.05 , 1.24 ) were higher in the incentive group , and the overall non-response rate was lower ( RR 0.68 ( 95 % CI 0.53 , 0.87 ) ) . Adjustment for injury severity and hospital of recruitment to MINT made no difference to these results , and there were no differences in results between the 4-month and 8-month follow up question naires . Analysis of costs suggested a cost of £ 67.29 per additional question naire returned . Conclusion Monetary incentives may be an effective way to increase the proportion of postal question naires returned and minimise loss to follow-up in clinical trials . Trial registration numberIS RCT Proper r and omisation means little if investigators can not include all r and omised participants in the primary analysis . Participants might ignore follow-up , leave town , or take aspartame when instructed to take aspirin . Exclusions before r and omisation do not bias the treatment comparison , but they can hurt generalisability . Eligibility criteria for a trial should be clear , specific , and applied before r and omisation . Readers should assess whether any of the criteria make the trial sample atypical or unrepresentative of the people in which they are interested . In principle , assessment of exclusions after r and omisation is simple : none are allowed . For the primary analysis , all participants enrolled should be included and analysed as part of the original group assigned ( an intent-to-treat analysis ) . In reality , however , losses frequently occur . Investigators should , therefore , commit adequate re sources to develop and implement procedures to maximise retention of participants . Moreover , research ers should provide clear , explicit information on the progress of all r and omised participants through the trial by use of , for instance , a trial profile . Investigators can also do secondary analyses on , for instance , per- protocol or as-treated participants . Such analyses should be described as secondary and non-r and omised comparisons . Mish and ling of exclusions causes serious method ological difficulties . Unfortunately , some explanations for mish and ling exclusions intuitively appeal to readers , disguising the seriousness of the issues . Creative mismanagement of exclusions can undermine trial validity Background There has been limited study of factors influencing response rates and attrition in online research . Online experiments were nested within the pilot ( study 1 , n = 3780 ) and main trial ( study 2 , n = 2667 ) phases of an evaluation of a Web-based intervention for hazardous drinkers : the Down Your Drink r and omized controlled trial ( DYD- RCT ) . Objectives The objective was to determine whether differences in the length and relevance of question naires can impact upon loss to follow-up in online trials . Methods A r and omized controlled trial design was used . All participants who consented to enter DYD- RCT and completed the primary outcome question naires were r and omized to complete one of four secondary outcome question naires at baseline and at follow-up . These question naires varied in length ( additional 23 or 34 versus 10 items ) and relevance ( alcohol problems versus mental health ) . The outcome measure was the proportion of participants who completed follow-up  at each of two follow-up intervals : study 1 after 1 and 3 months and study 2 after 3 and 12 months . Results At all four follow-up intervals there were no significant effects of additional question naire length on follow-up . R and omization to the less relevant question naire result ed in significantly lower rates of follow-up in two of the four assessment s made ( absolute difference of 4 % , 95 % confidence interval [ CI ] 0%-8 % , in both study 1 after 1 month and in study 2 after 12 months ) . A post hoc pooled analysis across all four follow-up intervals found this effect of marginal statistical significance ( unadjusted difference , 3 % , range 1%-5 % , P = .01 ; difference adjusted for prespecified covariates , 3 % , range 0%-5 % , P = .05 ) . Conclusions Apparently minor differences in study design decisions may have a measurable impact on attrition in trials . Further investigation is warranted of the impact of the relevance of outcome measures on follow-up rates and , more broadly , of the consequences of what we ask participants to do when we invite them to take part in research studies . Trial registration IS RCT N Register 31070347 ; http://www.controlled-trials.com/IS RCT N31070347/31070347 Archived by WebCite at ( http://www.webcitation.org/62cpeyYaY BACKGROUND A range of factors have been shown to affect the response rate to mailed question naires , but particular strategies to improve patients ' response in trials conducted in general practice require further study . METHODS Non-responders in a larger trial were r and omized to receive a telephone or recorded delivery reminder on the third contact . The cost of administration of each method was estimated . RESULTS Significantly more patients returned completed question naires when sent question naires by recorded delivery , although the cost per patient contacted was nearly three times more than for contact by telephone . CONCLUSION Our study indicates that sending reminders by recorded delivery , although more expensive , is more effective than telephone reminders for recruiting patients to a study in general practice using research question naires In this study , the authors sought to determine the effects of length and clarity on response rates and data quality for two food frequency question naires ( FFQs ) : the newly developed 36-page Diet History Question naire ( DHQ ) , design ed to be cognitively easier for respondents , and a 16-page FFQ developed earlier for the Prostate , Lung , Colorectal , and Ovarian ( PLCO ) Cancer Screening Trial . The PLCO Trial is a 23-year r and omized controlled clinical trial begun in 1992 . The sample for this sub study , which was conducted from January to April of 1998 , consisted of 900 control and 450 screened PLCO participants aged 55 - 74 years . Controls received either the DHQ or the PLCO FFQ by mail . Screenees , who had previously completed the PLCO FFQ at baseline , were administered the DHQ . Among controls , the response rate for both FFQs was 82 % . Average amounts of time needed by controls to complete the DHQ and the PLCO FFQ were 68 minutes and 39 minutes , respectively . Percentages of missing or uninterpretable responses were similar between instruments for questions on frequency of intake but were approximately 3 and 9 percentage points lower ( p < or = 0.001 ) in the DHQ for questions on portion size and use of vitamin/mineral supplements , respectively . Among screenees , response rates for the DHQ and the PLCO FFQ were 84 % and 89 % , respectively , and analyses of questions on portion size and supplement use showed few differences . These data indicated that the shorter FFQ was not better from the perspective of response rate and data quality , and that clarity and ease of administration may compensate for question naire length Background Loss to follow-up of trial participants represents a threat to research validity . To date , interventions design ed to increase participants ’ awareness of benefits to society of completing follow-up , and the impact of a telephone call from a senior female clinician and research er requesting follow-up have not been evaluated robustly . Purpose Trial 1 aim ed to evaluate the effect on trial follow-up of written information regarding the benefits of participation to society . Trial 2 aim ed to evaluate the effect on trial follow-up of a telephone call from a senior female clinician and research er . Methods Two single-blind r and omized controlled trials were nested within a larger trial , Txt2stop . In Trial 1 , participants were allocated using minimization to receive a refrigerator magnet and a text message emphasizing the benefits to society of completing follow-up , or to a control group receiving a simple reminder regarding follow-up . In Trial 2 , participants were r and omly allocated to receive a telephone call from a senior female clinician and research er , or to a control group receiving st and ard Txt2stop follow-up procedures . Results Trial 1 : 33.5 % ( 327 of 976 ) of the intervention group and 33.8 % ( 329 of 974 ) of the control group returned the question naire within 26 weeks of r and omization , risk ratio ( RR ) 0.99 ; 95 % confidence interval ( CI ) 0.88–1.12 . In all , 83.3 % ( 813 of 976 ) of the intervention group and 82.2 % ( 801 of/974 ) of the control group sent back the question naire within 30 weeks of r and omization , RR 1.01 ; 95 % CI 0.97 , 1.05 . Trial 2 : 31 % ( 20 of 65 ) of the intervention group and 32 % ( 20 of 62 ) of the control group completed trial follow-up , RR 0.93 ; 95%CI 0.44 , 1.98 . Conclusions In presence of other methods to increase follow-up neither experimental method ( refrigerator magnet and text message emphasizing participation 's benefits to society nor a telephone call from study 's principal investigator ) increased participant follow-up in the Txt2stop trial to test early  nutritional interventions  and prospect i ve observational cohorts . RCTs are generally accepted as method ologically the best approach for informing health policy . They can equalise unknown as well as known confounding factors and so can demonstrate causation ; they permit estimation of effect size and so can be used to assess likely Behavioral research has an important role in increasing and maintaining participation in disease prevention trials , both in interventions and in follow-up visits . We conducted a r and omized experiment among participants in the lung cancer chemoprevention trial , CARET ( Carotene and Retinol Efficacy Trial ) to test the effects of providing two incentives on retention . The items used for this study were a Certificate of Appreciation and one of two lapel pins , provided in a 2 2 design . Providing incentives , whether alone or in combination , had no statistically significant effect on retention by the two-year follow-up point . The successful implementation of this r and omized incentive study has two implication s for future research : ( 1 ) study of behavioral interventions and issues is feasible in the context of large controlled trials of disease end-points ; and ( 2 ) such study is necessary to determine 
    Output:
    
Most of the trials evaluated question naire response rather than ways to improve participants return to site for follow-up .
Monetary incentives and offers of monetary incentives increase postal and electronic question naire response .