## 3 Survey Design
Furthermore, investors can often be misled, simply due to the order or manner in which they have received information or the circumstances under which they make a decision; therefore, being aware and mindful of these biases can ultimately lead to optimal investment judgments being made. Consequently, survey questions were kept as direct and straightforward as possible and were pilot tested for wording and transparency of meaning. They were also inspired by other questions which already had an established place in the literature. Fourthly, the **operational details** of the survey are of high importance for the validation of results. The sample comprises 104 surveyed investors, the stock market holders in TSE (Tehran Stock Exchange). The study aims to analyse their behaviour based on the most well-known examples and cases of cognitive biases. In order to measure the tendency to exhibit these expected behaviours, we dedicated specific questions in the survey to analysing these biases. After some initial general questions regarding gender, age, experience, the preferred method of approach in the stock market and the amount of the stock market holder's investment, we asked questions that analysed the behaviour of the investor in terms of cognitive biases. We also included a question addressing investor's overall views of Iran's economic situation, which we believe can link the underlying approach of the investor--being either optimistic or pessimistic--to their individual thought process, which ultimately influences their choices around selling or buying stocks and mutual funds. Furthermore, the questions were based on the Likert scale for multiple choice answers, since this is the most widely used psychometric approach for asking the investors about their opinions or feelings about different stock market situations in a survey. Details of the survey are in the Appendix A. As will be shown in the following sections, this approach enables a valuable and reliable research sample to be obtained, in turn allowing conclusions to be drawn on the bundling of cognitive biases. Fifthly, we present **threats to validity**. We have analysed the existing research that (1) considered cognitive biases of investors on financial markets, (2) examined seven selected biases jointly, (3) analysed individual data from investors' surveys, and (4) examined the behavioural studies for Tehran Stock Exchange. We have screened the databases of Web of Science, Scopus, IEEE Xplore, ACM Digital Library, Science Direct, and Springer Link. Additionally, we ran forward and backward searches in Google Scholar and Research Gate. We looked for multiple combinations of \"stock exchange\", \"financial market\", \"Tehran Stock Exchange\", \"confirmation bias\", \"loss aversion\", \"availability cascade\", \"gambler's fallacy\", \"hot hand\", \"bandwagon effect\", \"Dunning-Kruger effect\". We focused on papers published since 2017 in the first round and since 2010 in the second round. The usefulness of the research was assessed based on the abstract. We found many papers that dealt with a given cognitive bias separately, which was not our interest. We did not find any papers which either analysed seven cognitive biases jointly or used unsupervised learning methods. All other papers presenting interesting approaches and findings were mentioned as references.