偏度和峰度

https://www.bilibili.com/video/BV1Hq4y1h7HA?spm_id_from=333.337.search-card.all.click&vd_source=bdbb5be671dc7bcfadbe64bf3d0d2f95

https://www.bilibili.com/video/BV11i4y1Z7Js?spm_id_from=333.337.search-card.all.click&vd_source=bdbb5be671dc7bcfadbe64bf3d0d2f95