[데이터사이언스] linear regression에서 t-test와 confidence interval

•  참고자료
  •  [confidence interval] https://www.khanacademy.org/math/ap-statistics/inference-slope-linear-regression/inference-slope/v/confidence-interval-slope
  •  [t-test] https://vitalflux.com/linear-regression-t-test-formula-example/
  •  [confidence interval]    https://www.youtube.com/watch?v=B0ClfLofRi8