 However, it has been shown that classical statistical approaches , like those based on the ordinary least squares estimator, fail to provide reliable confidence intervals when used with bandit data .
<clarity>  However, it has been shown that classical statistical approaches , like those based on the ordinary least squares estimator, fail to provide reliable confidence intervals when used with bandit data .
 However, it has been shown that classical statistical approaches , like those based on the ordinary least squares estimator, fail to provide valid confidence intervals when used with bandit data .