def filter_effect(self, analytes=None, stats=['mean', 'std'], filt=True):
        """
        Quantify the effects of the active filters.
        
        Parameters
        ----------
        analytes : str or list
            Which analytes to consider.
        stats : list
            Which statistics to calculate.
        file : valid filter string or bool
            Which filter to consider. If True, applies all
            active filters.
        
        Returns
        -------
        pandas.DataFrame
            Contains statistics calculated for filtered and
            unfiltered data, and the filtered/unfiltered ratio.
        """
        if analytes is None:
            analytes = self.analytes
        if isinstance(analytes, str):
            analytes = [analytes]
        
        # calculate filtered and unfiltered stats
        self.sample_stats(['La139', 'Ti49'], stats=stats, filt=False)
        suf = self.stats.copy()
        self.sample_stats(['La139', 'Ti49'], stats=stats, filt=filt)
        sf = self.stats.copy()
        
        # create dataframe for results
        cols = []
        for s in self.stats_calced:
            cols += ['unfiltered_{:}'.format(s), 'filtered_{:}'.format(s)] 

        comp = pd.DataFrame(index=self.samples,
                            columns=pd.MultiIndex.from_arrays([cols, [None] * len(cols)]))

        # collate stats
        for k, v in suf.items():
            vf = sf[k]
            for i, a in enumerate(v['analytes']):
                for s in self.stats_calced:
                    comp.loc[k, ('unfiltered_{:}'.format(s), a)] = v[s][i,0]
                    comp.loc[k, ('filtered_{:}'.format(s), a)] = vf[s][i,0]
        comp.dropna(0, 'all', inplace=True)
        comp.dropna(1, 'all', inplace=True)
        comp.sort_index(1, inplace=True)

        # calculate filtered/unfiltered ratios
        rats = []
        for s in self.stats_calced:
            rat = comp.loc[:, 'filtered_{:}'.format(s)] / comp.loc[:, 'unfiltered_{:}'.format(s)]
            rat.columns = pd.MultiIndex.from_product([['{:}_ratio'.format(s)], rat.columns])
            rats.append(rat)
        
        # join it all up
        comp = comp.join(pd.concat(rats, 1))
        comp.sort_index(1, inplace=True)
        
        return comp.loc[:, (pd.IndexSlice[:], pd.IndexSlice[analytes])]
Quantify the effects of the active filters.
        
        Parameters
        ----------
        analytes : str or list
            Which analytes to consider.
        stats : list
            Which statistics to calculate.
        file : valid filter string or bool
            Which filter to consider. If True, applies all
            active filters.
        
        Returns
        -------
        pandas.DataFrame
            Contains statistics calculated for filtered and
            unfiltered data, and the filtered/unfiltered ratio.