***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 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: 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 Objective : To assess whether length of question naire affects response rates . Methods : A quasi-r and omised trial of women aged 70 years and over in a general practice in Engl and .  Three question naires of different lengths : a clinical question naire ( four pages ) ; the same question naire plus the EuroQol ( five pages ) ; the same question naire plus the SF-12 ( seven pages ) . The impact of length on the proportion of returned question naires and item completion rates was assessed . Results : In total , 847 question naires were mailed ;  response rates were 49 % , 49 % and 40 % to the short , medium and long question naires , respectively . This difference was statistically significant when the short question naire was compared against the longest instrument ( 9 % difference ; 95 % confidence interval ( CI ) of difference=0.3 % to 16.6 % ) . Item completion rates for the clinical question naire did not differ . Respondents did not differ in age or self-reported health status between the three groups . Conclusions : Increasing the length of a question naire from five to seven pages reduces response rates from women aged 70 years and over . However , lengthening a question naire does not seem to affect the quality of responses to questions near the front of the question naire CONTEXT Factors that interfere with the ability to interpret assessment scores or ratings in the proposed manner threaten validity . To be interpreted in a meaningful manner , all assessment s in medical education require sound , scientific evidence of validity . PURPOSE The purpose of this essay is to discuss 2 major threats to validity : construct under-representation ( CU ) and construct-irrelevant variance ( CIV ) . Examples of each type of threat for written , performance and clinical performance examinations are provided . DISCUSSION The CU threat to validity refers to undersampling the content domain . Using too few items , cases or clinical performance observations to adequately generalise to the domain represents CU . Variables that systematic ally ( rather than r and omly ) interfere with the ability to meaningfully interpret scores or ratings represent CIV . Issues such as flawed test items written at inappropriate reading levels or statistically biased questions represent CIV in written tests . For performance examinations , such as st and ardised patient examinations , flawed cases or cases that are too difficult for student ability contribute CIV to the assessment . For clinical performance data , systematic rater error , such as halo or central tendency error , represents CIV . The term face validity is rejected as representative of any type of legitimate validity evidence , although the fact that the appearance of the assessment may be an important characteristic other than validity is acknowledged . CONCLUSIONS There are multiple threats to validity in all types of assessment in medical education . Methods to eliminate or control validity threats are suggested 
    Output:
    
The model of workplace learning showed to be a useful framework for developing EFFECT , which incorporates the CanMEDS competencies and proved to be valid and reliable