I am going to compare the efficiency of a sample banks using data envelopment analysis (DEA) for one year. The banks sample will be divided into three groups; i.e., Islamic, conventional, and mixed banks. Mixed banks are banks that provide both Islamic and conventional services in the same time.

I have two questions:

1-Is it logic to compare efficiency results for the three groups of banks for just one year?. My objective is to compare the efficiency scores, not tracking the scores through different years.

2-Is it logic to use three groups of banks; i.e., Islamic, conventional, and mixed banks?. Previous studies compared only two groups of banks; i.e., Islamic and conventional banks. However, conventional banks have not been studied before.