AWR1843BOOST: ADC Sample Raw Data Format

hi，

I have read the file "SWRA-518B mmwave Radar Device ADC Raw Data Capture" ，and I already know the data format.

when ADC chip sample the mixing analog signals, why is 4 bytes per sample when I  choose the data format 'complex1, I first, Q later'?

as I know , 2 bytes per sample is correct and easily understood.   Could you tell me what's meaning of '4 bytes per sample' ?

In addition,

according to the guide file swra518b, when choose complex1, whether the sequence of raw data is  I0 Q0 I1 Q1 I2 Q2 I3 Q3 I4 Q4.....? 

thanks