what kind of study design is used? Is the correct statistical test used to analyze the data?

what kind of study design is used? Is the correct statistical test used to analyze the data?

The purpose of the study is to quantify the level of emotional understanding as well as other skills related to emotional intelligence among substance abusers. Do substance abusers have a different level of emotional understanding than the general population? The researchers used a convenience sampling method to obtain a sample of 40 substance abusers who have just entered residential treatment. The participants completed the Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT) to measure their emotional intelligence. Note, the ability based model of emotional intelligence measures four branches: 1) the ability to identify emotions in facial expressions, 2) the ability to use emotional information to facilitate thoughts, 3) the ability to understand emotions, and 4) the ability to regulate emotions in the self and others. This assessment was selected to provide information on emotional understanding and other abilities under the umbrella of emotional intelligence. The mean score on the MSCEIT for the population is 100. The null hypothesis states there will be no difference between the scores on the MSCEIT for substance abusers when compared to the general population. A single sample t-test was used to analyze the data.