This function checks and deals with different types of mixed frequency models. When there is a mixed frequency within a variable, it tries to remove
     
    
    Usage
    check_frequencies(full_data, quiet)
 
    
    Arguments
- full_data
- The full dataset that is used in the model 
- quiet
- Logical with default = FALSE. Should messages be displayed?
These messages are intended to give more information about the estimation
and data retrieval process. 
 
    
    Value
    A list with the updated full_data and the frequency of the data