The causal connection between phenomena means that the existence of a phenomenon necessarily causes another phenomenon to occur, then there is a causal connection between the two phenomena. One of the methods to explore the causal relationship between phenomena is the same method, which means: The phenomenon under study occurs on different occasions, and only one situation is common in each occasion, then the only common situation is causally related to the phenomenon. According to the above definition, the correct application of the same method is as follows:. ["comparing a group of patients with gastric ulcer and a group of non-patients. The only difference between the two groups is that the patient's stomach is infected with H. pylori, and the non-patient is not infected. It can be inferred that H. pylori infection may be the cause of gastric ulcer.", 'comparing students with different creativity, and found that when other things are the same, the stronger the divergent thinking, the stronger the creativity; vice versa. It follows that there is a causal connection between divergent thinking and creativity.', "there were many people poisoning in a village, the age, sex, family situation, and diet of the villagers were different, but they all cited water from public wells. The police inferred that the well water might be the cause of the villagers' poisoning.", 'Some psychologists have found that 75% of people with antisocial personality are narrow-minded. It can be inferred that narrow-mindedness may be the cause of the formation of antisocial personality.']