Post hoc fallacy, derived from the Latin phrase *post hoc, ergo propter hoc* meaning “after this, therefore because of this,” is a common logical error in research and reasoning. It occurs when a researcher assumes that because one event follows another, the first event must have caused the second. In psychological research, this fallacy can lead to incorrect conclusions about cause-and-effect relationships, thereby reducing the validity of findings. Distinguishing between correlation and causation is essential to avoid this error. In psychology, many variables influence human behavior, emotions, cognition, and personality. Simply observing that one event precedes another does not establish a causal relationship. For example, if a person's anxiety decreases after attending a motivational seminar, it would be a post hoc fallacy to conclude that the seminar alone caused the improvement. The reduction in anxiety may also be due to medication, social support, natural recovery, or other life changes occurring during the same period. The post hoc fallacy frequently arises in observational studies where researchers do not control variables. Since these studies only observe naturally occurring events, it is difficult to determine whether one variable truly causes another. Experimental research methods are specifically designed to minimize this problem by manipulating the independent variable while controlling extraneous variables. Random assignment, control groups, and standardized procedures help establish whether a genuine causal relationship exists. An example in educational psychology illustrates this fallacy. Suppose a school introduces a mindfulness program, and students' academic performance improves