Read the case study below and answer the question at the end .

BANKS START IMAGE REPAIR OVER FINANCIAL CRISIS

In the first months of 2010, U.S. Banks have launched a campaign that aims to win back trust of their consumers and repair their battered images. For banks, it is very important to rectify the violation of trust caused by the financial crisis if the financial sector is to be brought back to health. A large-scale image-improvement campaign should therefore convey that banks have learned from their mistakes and are taking less risk with their customers' money. The challenge facing the industry is a difficult one however: In a poll conducted by the Gallup Organization in 2009, only 19% of Americans surveyed was confident in the integrity of banks, down from 41% 4 years earlier and the lowest level since Gallup began examining the integrity of bankers in 1976. And yet, even though banks realize that reputation improvement will be a slow, labor-intensive and cost-intensive operation, Rachel Dawes, a marketing executive of The Citizens Bank of America, points out that the financial services industry is dedicated to earning back the trust of the American people, and is engaging in a comprehensive effort to communicate directly with them. According to Rachel "it is clear that we have made mistakes and we recognize that we cannot simply advertise our way out of these issues."

Ralph Tanner, a Master student in Marketing Management is using his Masters project to investigate how U.S. banks can improve their image. He believes that understanding the current and desired image is vital to effectively repairing the battered images of banks. Therefore, Ralph wants to thoroughly understand consumers' perceptions of banks. Six weeks ago, he and his thesis supervisor have concluded that both qualitative and quantitative research is needed to develop and test a conceptual model of brand image of U.S. banks. This model should enable banks, such as The Citizens Bank of America, to gradually improve their image.

Just two weeks ago, Ralph has executed the first part of his project; an exploratory, qualitative study that aimed to identify the factors that play a role in shaping the overall image of U.S. banks. This qualitative study has resulted in a conceptual model of the image of banks in the U.S. "through the eyes of the consumer". At this moment, Ralph is working on the quantitative study. This study aims to test his conceptual model, generalize the findings of the qualitative study to the population, and eventually establish how banks can effectively improve their corporate image. Ralph has spent the last few days on thinking about the method, sample, and procedure of his quantitative study. Because he finds that it is important to test the relationships between the variables in his conceptual model in a natural setting, Ralph has opted for a field study with minimal researcher interference. For this purpose, he has developed a questionnaire, in which consumers are asked to provide their overall perceptions toward banks and their perceptions toward six relevant factors that shape this overall image, such as diligence, competence, and reliability.

An understanding of the factors that shape overall image may help banks to improve their overall image. For instance, if banks are momentarily perceived as not very reliable, and if this factor turns out to have a significant effect on overall image, efforts in improving reliability will eventually result in a more positive overall image of banks. Ralph has decided to use an indirect method (regression analysis) to establish the effect of these contributing factors on the overall image of U.S. banks.

Ralph wants to send the questionnaire he has developed to everybody in his mail directory. This mail directory includes friends, family, members of the Golden Gate Park tennis club and the Phi Rho Omega Marketing Students association, and the staff of Da Paolo, a small Italian restaurant where Ralph has a part-time job allowing him to earn some extra cash during the weekends. His mail directory includes a total number of 254 people.

question :- Is Ralph putting forward a probability or a non-probability sampling technique in his quantitative study?