“…Of the 23 studies included in the review, 17 studies used piloted, trialled or previously published survey instruments (Additional File 3) 43,44,47,48,[50][51][52][53][54][55][56][57][58][59][60][61]64,65 . Only 11 studies used an adequate sampling frame to achieve a representative sample 45,46,50,51,[54][55][56]58,59,61,62 and 10 studies were deemed to use an adequate selection process 47,50,51,[54][55][56][57]59,61,62 . Of the studies that used adequate sampling frames, eight used existing online research panels 46,50,54,56,58,59,61,62 (two most common being Qualtrics, n = 2 54,56 and the AmeriSpeak panel, n = 2 50,59 ).…”