title: GridSearchCV & RandomizedSearchCV - do you refit the model after running
body: <p>I have some test and train data, the test data does not have any dependant variables.</p>
  
  <p>I'm currently running a GridSearchCV or RandomizedSearchCV to find the best paramaters.</p>
  
  <p>Should I pass all of my <strong>"test"</strong> X &amp; y values into a GridSearchCV or RandomizedSearchCV? </p>
  
  <p>I understand it does a cross validation, so I believe its fine to? </p>
  
  <p>But if this is the case, what data has the best_estimator been fit with? All of it? Or data from one of the folds?</p>
  
  <p>Do I need to refit the full set of test data after?</p>