Pschologists conducted a study to investigate if there is a correlation between personality and length of mobile phone text messages. Twenty students aged 16-19 from one AS psycholgy class attending a college in London were used. Personality was assessed by asking participents to rate themselves using a scale of 1 (very introvert - shy) to 10 (very extrovert - outgoing). The average number of words used in a text message over a period of week was obtained from the phones. Outline one strength and one weakness used in this study.