[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-detail-35929":3,"doc-seo-35929":28},{"code":4,"msg":5,"data":6},0,"success",{"doc_id":7,"user_id":8,"nickname":9,"user_avatar":10,"doc_module":4,"category_id":11,"category_name":12,"doc_title":13,"doc_description":14,"doc_content":15,"file_id":16,"file_url":17,"file_type":18,"file_size":19,"view_count":4,"is_deleted":4,"is_public":20,"is_downloadable":20,"audit_status":20,"page_count":11,"language":21,"language_code":22,"site_id":23,"html_lang":22,"table_of_contents":24,"faqs":25,"seo_title":13,"seo_description":14,"update_tm":26,"read_time":27},35929,1099513958762,"Logic","https://ap-avatar.wpscdn.com/avatar/1000023916a998db790?x-image-process=image/resize,m_fixed,w_180,h_180&k=1782109480056885918",8,"Research & Report","Correction of Item-Total Correlations in Item Analysis","Item analysis commonly uses the biserial correlation between an item and the total test score, but this overlap can inflate discrimination estimates because the item contributes to the total. The text derives two corrected approaches to remove this spuriousness when correlating an item with the remaining n−1 items, comparing results with Zubin’s and Guilford’s formulas. One new coefficient is shown to be invariant to test length, supporting more reliable discrimination indexing.","","cbCaip9Lut4efwY2","https://ap.wps.com/l/cbCaip9Lut4efwY2","pdf",380008,1,"English","en",105,"# Overview of Item-Total Correlations\n## Bias from Item Inclusion in the Total Score\n# Zubin's and Guilford's Formulas\n## Spuriousness Correction Approaches\n# The Biserial Item-Remainder Coefficient\n## Definition and Derivation","[{\"question\":\"Why can the biserial correlation between an item and the total test be misleading in item analysis?\",\"answer\":\"Because the item is part of the total test score, the correlation is inflated by overlap. The shorter the test, the greater the inflation, even under conditions where items have no true relation to the measured total construct.\"},{\"question\":\"What do Zubin’s and Guilford’s formulas address in the context of item-total correlations?\",\"answer\":\"They propose correction methods to reduce the spurious inflation caused by including the target item in the total score. Guilford critiques Zubin’s formula and provides an alternative corrected expression.\"},{\"question\":\"What is the purpose of the “biserial item-remainder coefficient” derived in the document?\",\"answer\":\"To obtain the biserial correlation between an item and the remaining n−1 items, excluding the item itself from the test total. The derivation uses relationships among covariances derived from the interitem variance-covariance structure.\"}]",1782766832,20,null]