{"id":1391,"date":"2023-06-22T02:22:36","date_gmt":"2023-06-22T02:22:36","guid":{"rendered":"https:\/\/content.one.lumenlearning.com\/introstatstest\/chapter\/introduction-to-chi-square-statistics-background-youll-need-1\/"},"modified":"2025-05-16T23:03:08","modified_gmt":"2025-05-16T23:03:08","slug":"introduction-to-chi-square-statistics-background-youll-need-1","status":"publish","type":"chapter","link":"https:\/\/content.one.lumenlearning.com\/introstatstest\/chapter\/introduction-to-chi-square-statistics-background-youll-need-1\/","title":{"raw":"Module 14: Background You'll Need 1","rendered":"Module 14: Background You&#8217;ll Need 1"},"content":{"raw":"<section class=\"textbox learningGoals\">\r\n<ul>\r\n\t<li>Calculate probabilities and expected counts for a categorical variable<\/li>\r\n<\/ul>\r\n<\/section>\r\n<h2>Italian Football (or in America, soccer)<\/h2>\r\n<p><img class=\"alignleft wp-image-1426\" src=\"https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/27\/2023\/06\/22022236\/download.png\" alt=\"A soccerball\" width=\"206\" height=\"207\" \/><\/p>\r\n<p>In Italy, youth football leagues create cohorts of children based on year of birth.<\/p>\r\n<p>For example, children born in 2015 only played with other children born in that same year. If a child was born on December 31, 2014, they played with the 2014 cohort (rather than the younger 2015 cohort). So, children born earlier in the year (e.g., January or February) tend to be the eldest players in their leagues. Children born later in the year (e.g., November or December) tend to be the youngest players in their leagues.<\/p>\r\n<p>Could this seemingly unimportant practice\u2014grouping by year of birth\u2014have an effect on players\u2019 later football careers?<\/p>\r\n<section class=\"textbox tryIt\">[ohm2_question hide_question_numbers=1]2284[\/ohm2_question]<\/section>\r\n<section class=\"textbox tryIt\">[ohm2_question hide_question_numbers=1]2285[\/ohm2_question]<\/section>\r\n<p>In reality, birth rates are not the same between quarters of the year. Some quarters are longer (have more days), and different cultures have different preferences for times of birth.<\/p>\r\n<section class=\"textbox tryIt\">[ohm2_question hide_question_numbers=1]2287[\/ohm2_question][footnote]Fumarco, L. &amp; Rossi, G. (2018, August 8). The relative age effect on labour market outcomes - Evidence from Italian football. European Sport Management Quarterly, 18(4), 501\u2013516. DOI: 10.1080\/16184742.2018.1424225[\/footnote]<\/section>\r\n<section class=\"textbox tryIt\">[ohm2_question hide_question_numbers=1]2288[\/ohm2_question]<\/section>\r\n<section class=\"textbox tryIt\">[ohm2_question hide_question_numbers=1]2289[\/ohm2_question]<\/section>","rendered":"<section class=\"textbox learningGoals\">\n<ul>\n<li>Calculate probabilities and expected counts for a categorical variable<\/li>\n<\/ul>\n<\/section>\n<h2>Italian Football (or in America, soccer)<\/h2>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignleft wp-image-1426\" src=\"https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/27\/2023\/06\/22022236\/download.png\" alt=\"A soccerball\" width=\"206\" height=\"207\" \/><\/p>\n<p>In Italy, youth football leagues create cohorts of children based on year of birth.<\/p>\n<p>For example, children born in 2015 only played with other children born in that same year. If a child was born on December 31, 2014, they played with the 2014 cohort (rather than the younger 2015 cohort). So, children born earlier in the year (e.g., January or February) tend to be the eldest players in their leagues. Children born later in the year (e.g., November or December) tend to be the youngest players in their leagues.<\/p>\n<p>Could this seemingly unimportant practice\u2014grouping by year of birth\u2014have an effect on players\u2019 later football careers?<\/p>\n<section class=\"textbox tryIt\"><iframe loading=\"lazy\" id=\"ohm2284\" class=\"resizable\" src=\"https:\/\/ohm.one.lumenlearning.com\/multiembedq.php?id=2284&theme=lumen&iframe_resize_id=ohm2284&source=tnh\" width=\"100%\" height=\"150\"><\/iframe><\/section>\n<section class=\"textbox tryIt\"><iframe loading=\"lazy\" id=\"ohm2285\" class=\"resizable\" src=\"https:\/\/ohm.one.lumenlearning.com\/multiembedq.php?id=2285&theme=lumen&iframe_resize_id=ohm2285&source=tnh\" width=\"100%\" height=\"150\"><\/iframe><\/section>\n<p>In reality, birth rates are not the same between quarters of the year. Some quarters are longer (have more days), and different cultures have different preferences for times of birth.<\/p>\n<section class=\"textbox tryIt\"><iframe loading=\"lazy\" id=\"ohm2287\" class=\"resizable\" src=\"https:\/\/ohm.one.lumenlearning.com\/multiembedq.php?id=2287&theme=lumen&iframe_resize_id=ohm2287&source=tnh\" width=\"100%\" height=\"150\"><\/iframe><a class=\"footnote\" title=\"Fumarco, L. &amp; Rossi, G. (2018, August 8). The relative age effect on labour market outcomes - Evidence from Italian football. European Sport Management Quarterly, 18(4), 501\u2013516. DOI: 10.1080\/16184742.2018.1424225\" id=\"return-footnote-1391-1\" href=\"#footnote-1391-1\" aria-label=\"Footnote 1\"><sup class=\"footnote\">[1]<\/sup><\/a><\/section>\n<section class=\"textbox tryIt\"><iframe loading=\"lazy\" id=\"ohm2288\" class=\"resizable\" src=\"https:\/\/ohm.one.lumenlearning.com\/multiembedq.php?id=2288&theme=lumen&iframe_resize_id=ohm2288&source=tnh\" width=\"100%\" height=\"150\"><\/iframe><\/section>\n<section class=\"textbox tryIt\"><iframe loading=\"lazy\" id=\"ohm2289\" class=\"resizable\" src=\"https:\/\/ohm.one.lumenlearning.com\/multiembedq.php?id=2289&theme=lumen&iframe_resize_id=ohm2289&source=tnh\" width=\"100%\" height=\"150\"><\/iframe><\/section>\n<hr class=\"before-footnotes clear\" \/><div class=\"footnotes\"><ol><li id=\"footnote-1391-1\">Fumarco, L. &amp; Rossi, G. (2018, August 8). The relative age effect on labour market outcomes - Evidence from Italian football. European Sport Management Quarterly, 18(4), 501\u2013516. DOI: 10.1080\/16184742.2018.1424225 <a href=\"#return-footnote-1391-1\" class=\"return-footnote\" aria-label=\"Return to footnote 1\">&crarr;<\/a><\/li><\/ol><\/div>","protected":false},"author":8,"menu_order":2,"template":"","meta":{"_candela_citation":"[]","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"part":1388,"module-header":"background_you_need","content_attributions":[],"internal_book_links":[],"video_content":null,"cc_video_embed_content":{"cc_scripts":"","media_targets":[]},"try_it_collection":null,"_links":{"self":[{"href":"https:\/\/content.one.lumenlearning.com\/introstatstest\/wp-json\/pressbooks\/v2\/chapters\/1391"}],"collection":[{"href":"https:\/\/content.one.lumenlearning.com\/introstatstest\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/content.one.lumenlearning.com\/introstatstest\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/introstatstest\/wp-json\/wp\/v2\/users\/8"}],"version-history":[{"count":10,"href":"https:\/\/content.one.lumenlearning.com\/introstatstest\/wp-json\/pressbooks\/v2\/chapters\/1391\/revisions"}],"predecessor-version":[{"id":6855,"href":"https:\/\/content.one.lumenlearning.com\/introstatstest\/wp-json\/pressbooks\/v2\/chapters\/1391\/revisions\/6855"}],"part":[{"href":"https:\/\/content.one.lumenlearning.com\/introstatstest\/wp-json\/pressbooks\/v2\/parts\/1388"}],"metadata":[{"href":"https:\/\/content.one.lumenlearning.com\/introstatstest\/wp-json\/pressbooks\/v2\/chapters\/1391\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/content.one.lumenlearning.com\/introstatstest\/wp-json\/wp\/v2\/media?parent=1391"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/introstatstest\/wp-json\/pressbooks\/v2\/chapter-type?post=1391"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/introstatstest\/wp-json\/wp\/v2\/contributor?post=1391"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/introstatstest\/wp-json\/wp\/v2\/license?post=1391"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}