Computing the cronbach's alpha is the way to check if the:

Most researchers, which include market researchers and Academic researchers or any other researchers prefer the use of multiple-item questionnaires because it enables researchers to obtain more reliable measures even though it will cost them more and also time consuming. Most researchers have reported that the most frequently reliability statistic for multiple-item scales is Cronbach’s coefficient alpha hence Computing the cronbach's alpha is the way most researchers check if the Multi-item measure is reliable.