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Low density enables inequality to rise again, creating a perpetually unstable equilibrium confirmed with a structural equation model over more than 100 years.",{"@graph":14,"@context":73},[15,34,56],{"@type":16,"itemListElement":17},"BreadcrumbList",[18,23,27,31],{"item":19,"name":20,"@type":21,"position":22},"https://docshare.wps.com","Home","ListItem",1,{"item":24,"name":25,"@type":21,"position":26},"https://docshare.wps.com/template/","Template",2,{"item":28,"name":29,"@type":21,"position":30},"https://docshare.wps.com/template/presentations/","Presentations",3,{"item":32,"name":10,"@type":21,"position":33},"https://docshare.wps.com/template/vortex-between-union-membership-and-inequality-final/177649/",4,{"url":32,"name":10,"@type":35,"image":36,"author":41,"headline":10,"publisher":44,"fileFormat":47,"inLanguage":8,"description":12,"dateModified":48,"datePublished":49,"encodingFormat":47,"isAccessibleForFree":50,"interactionStatistic":51},"DigitalDocument",{"url":37,"@type":38,"width":39,"height":40},"https://docshare.wps.com/thumbnails/vortex-between-union-membership-and-inequality-final/177649.png","ImageObject",442,249,{"name":42,"@type":43},"Mali","Person",{"url":19,"name":45,"@type":46},"DocShare","Organization","application/vnd.openxmlformats-officedocument.wordprocessingml.document","2026-10-19","2026-09-02",true,{"@type":52,"interactionType":53,"userInteractionCount":55},"InteractionCounter",{"@type":54},"ViewAction",10,{"@type":57,"mainEntity":58},"FAQPage",[59,65,69],{"name":60,"@type":61,"acceptedAnswer":62},"What does the prey-predator model imply about unions and inequality over the long run?","Question",{"text":63,"@type":64},"It implies that trade unions and income inequality influence each other in a cyclical predator–prey relationship rather than a simple contemporaneous correlation.","Answer",{"name":66,"@type":61,"acceptedAnswer":67},"How does inequality affect union membership according to the long-run evidence?",{"text":68,"@type":64},"Higher inequality leads to higher union membership after a time lag, contradicting the usual short-run view that inequality and union density move together negatively.",{"name":70,"@type":61,"acceptedAnswer":71},"How do the authors explain the mechanism behind the time-lagged cycle?",{"text":72,"@type":64},"Unions recruit to fight high inequality; when inequality falls, unions lose recruiting capacity after a lag, allowing inequality to increase again and re-incentivize membership.","https://schema.org",{"og:url":32,"og:type":75,"og:title":10,"og:site_name":45,"og:description":12},"article",{"robots":77,"canonical":32},"index,follow",{"doc_id":79,"site_id":7},177649,1791730640,{"code":4,"msg":82,"data":83},"success",[84,88,93,98,103,108,113,118,123],{"id":85,"doc_module":22,"doc_module_name":25,"category_name":29,"show_sort_weight":86,"slug":87},11,90,"presentations",{"id":89,"doc_module":22,"doc_module_name":25,"category_name":90,"show_sort_weight":91,"slug":92},12,"Resumes",80,"resumes",{"id":94,"doc_module":22,"doc_module_name":25,"category_name":95,"show_sort_weight":96,"slug":97},14,"Invoices",70,"invoices",{"id":99,"doc_module":22,"doc_module_name":25,"category_name":100,"show_sort_weight":101,"slug":102},15,"Posters",60,"posters",{"id":104,"doc_module":22,"doc_module_name":25,"category_name":105,"show_sort_weight":106,"slug":107},16,"Social Media",50,"social-media",{"id":109,"doc_module":22,"doc_module_name":25,"category_name":110,"show_sort_weight":111,"slug":112},17,"Forms",40,"forms",{"id":114,"doc_module":22,"doc_module_name":25,"category_name":115,"show_sort_weight":116,"slug":117},18,"Letters",30,"letters",{"id":119,"doc_module":22,"doc_module_name":25,"category_name":120,"show_sort_weight":121,"slug":122},21,"Paper Templates",5,"papers-templates",{"id":124,"doc_module":22,"doc_module_name":25,"category_name":125,"show_sort_weight":4,"slug":126},158,"General","general-158",{"code":4,"msg":82,"data":128},{"doc_id":79,"user_id":129,"nickname":42,"user_avatar":130,"doc_module":22,"category_id":85,"category_name":29,"doc_title":10,"doc_description":12,"doc_content":131,"file_id":132,"file_url":133,"file_type":134,"file_size":135,"view_count":55,"is_deleted":4,"is_public":22,"is_downloadable":22,"audit_status":22,"page_count":136,"language":137,"language_code":8,"site_id":7,"html_lang":8,"table_of_contents":138,"faqs":139,"seo_title":140,"seo_description":12,"update_tm":141,"read_time":142},2336475104362,"https://ap-avatar.wpscdn.com/avatar/22000c4c46a41b752dd?x-image-process=image/resize,m_fixed,w_180,h_180&k=1786595829695023868","A prey-predator model of trade union density and inequality in 12 advanced capitalisms since the early 20th century\nAbstract\nWe show that in the long historical run, trade unions and income inequality influence each other according to a prey and predator model. As is well-known, high current inequality goes along with low current trade union membership. However, using long-run historical data, we show that high inequality leads to higher, not lower union membership with a time lag. This is likely the case because trade unions recruit members to fight high inequality. Therefore, by lowering inequality, unions – again with a time lag – destroy their capacity to recruit members. Low trade union membership opens the way for inequality to increase, and higher inequality then re-incentives workers to join unions. Using a structural equation model with data on trade union membership and income inequality, we show how trade union membership and income inequality mutually cause each other in a perpetually instable equilibrium in twelve countries over more than 100 years.\nKeywords\nTrade union density, inequality, prey-predator model, top incomes\n\u000f\nIntroduction\nAn extensive literature is concerned with the determinants of trade union membership \u0013 ADDIN EN.CITE \u003CEndNote>\u003CCite>\u003CAuthor>Wallerstein\u003C/Author>\u003CYear>2000\u003C/Year>\u003CRecNum>1781\u003C/RecNum>\u003CPrefix>see the review in \u003C/Prefix>\u003CDisplayText>(see the review in Wallerstein and Western, 2000)\u003C/DisplayText>\u003Crecord>\u003Crec-number>1781\u003C/rec-number>\u003Cforeign-keys>\u003Ckey app=\"EN\" db-id=\"w5vds52ahdv2vxepz9tx0etjarf25zrzpxzf\" timestamp=\"1422705257\">1781\u003C/key>\u003C/foreign-keys>\u003Cref-type name=\"Journal Article\">17\u003C/ref-type>\u003Ccontributors>\u003Cauthors>\u003Cauthor>Wallerstein, Michael\u003C/author>\u003Cauthor>Western, Bruce\u003C/author>\u003C/authors>\u003C/contributors>\u003Ctitles>\u003Ctitle>Unions in Decline? What Has Changed and Why\u003C/title>\u003Csecondary-title>Annual Review of Political Science\u003C/secondary-title>\u003C/titles>\u003Cperiodical>\u003Cfull-title>Annual Review of Political Science\u003C/full-title>\u003C/periodical>\u003Cpages>355-377\u003C/pages>\u003Cvolume>3\u003C/volume>\u003Cnumber>1\u003C/number>\u003Cdates>\u003Cyear>2000\u003C/year>\u003C/dates>\u003Curls>\u003Crelated-urls>\u003Curl>http://www.annualreviews.org/doi/abs/10.1146/annurev.polisci.3.1.355\u003C/url>\u003C/related-urls>\u003C/urls>\u003Celectronic-resource-num>doi:10.1146/annurev.polisci.3.1.355\u003C/electronic-resource-num>\u003C/record>\u003C/Cite>\u003C/EndNote>\u0014(\u0013 HYPERLINK \\l \"_ENREF_42\" \\o \"Wallerstein, 2000 #1781\" \u0014see the review in Wallerstein and Western, 2000\u0015)\u0015. Another, similarly vast literature, explains what causes income inequality \u0013 ADDIN EN.CITE \u003CEndNote>\u003CCite>\u003CAuthor>Neckerman\u003C/Author>\u003CYear>2007\u003C/Year>\u003CRecNum>501\u003C/RecNum>\u003CPrefix>see the review by \u003C/Prefix>\u003CDisplayText>(see the review by Neckerman and Torche, 2007; Kenworthy, 2007)\u003C/DisplayText>\u003Crecord>\u003Crec-number>501\u003C/rec-number>\u003Cforeign-keys>\u003Ckey app=\"EN\" db-id=\"w5vds52ahdv2vxepz9tx0etjarf25zrzpxzf\" timestamp=\"1417104601\">501\u003C/key>\u003Ckey app=\"ENWeb\" db-id=\"\">0\u003C/key>\u003C/foreign-keys>\u003Cref-type name=\"Journal Article\">17\u003C/ref-type>\u003Ccontributors>\u003Cauthors>\u003Cauthor>Neckerman, Kathryn M.\u003C/author>\u003Cauthor>Florencia Torche\u003C/author>\u003C/authors>\u003C/contributors>\u003Ctitles>\u003Ctitle>Inequality: Causes and Consequences\u003C/title>\u003Csecondary-title>Annual Review of Sociology\u003C/secondary-title>\u003C/titles>\u003Cperiodical>\u003Cfull-title>Annual Review of Sociology\u003C/full-title>\u003C/periodical>\u003Cpages>335–57\u003C/pages>\u003Cvolume>33\u003C/volume>\u003Ckeywords>\u003Ckeyword>Social inequality\u003C/keyword>\u003C/keywords>\u003Cdates>\u003Cyear>2007\u003C/year>\u003C/dates>\u003Curls>\u003C/urls>\u003C/record>\u003C/Cite>\u003CCite>\u003CAuthor>Kenworthy\u003C/Author>\u003CYear>2007\u003C/Year>\u003CRecNum>660\u003C/RecNum>\u003Crecord>\u003Crec-number>660\u003C/rec-number>\u003Cforeign-keys>\u003Ckey app=\"EN\" db-id=\"w5vds52ahdv2vxepz9tx0etjarf25zrzpxzf\" timestamp=\"1417104891\">660\u003C/key>\u003Ckey app=\"ENWeb\" db-id=\"\">0\u003C/key>\u003C/foreign-keys>\u003Cref-type name=\"Journal Article\">17\u003C/ref-type>\u003Ccontributors>\u003Cauthors>\u003Cauthor>Lane Kenworthy\u003C/author>\u003C/authors>\u003C/contributors>\u003Ctitles>\u003Ctitle>Inequality and Sociology\u003C/title>\u003Csecondary-title>American Behavioral Scientist\u003C/secondary-title>\u003C/titles>\u003Cperiodical>\u003Cfull-title>American Behavioral","cbCaieOUVzrXJZsU","https://ap.wps.com/l/cbCaieOUVzrXJZsU","docx",232366,22,"English","# Introduction\n## Determinants of trade union membership\n## Causes of income inequality\n## Mutual relationship between inequality and unions\n## Modeling strategy (prey-predator and structural equations)","[{\"question\":\"What does the prey-predator model imply about unions and inequality over the long run?\",\"answer\":\"It implies that trade unions and income inequality influence each other in a cyclical predator–prey relationship rather than a simple contemporaneous correlation.\"},{\"question\":\"How does inequality affect union membership according to the long-run evidence?\",\"answer\":\"Higher inequality leads to higher union membership after a time lag, contradicting the usual short-run view that inequality and union density move together negatively.\"},{\"question\":\"How do the authors explain the mechanism behind the time-lagged cycle?\",\"answer\":\"Unions recruit to fight high inequality; when inequality falls, unions lose recruiting capacity after a lag, allowing inequality to increase again and re-incentivize membership.\"}]","Vortex between union membership and inequality - FINAL | DOCX",1788328725,8]