Statistical methods form the backbone of psychological research because they provide systematic procedures for organizing, analyzing, and interpreting data related to human behavior and mental processes. Among these methods, descriptive and inferential statistics play central roles. While descriptive statistics focus on summarizing and presenting data in a meaningful form, inferential statistics extend beyond the immediate data to draw conclusions about larger populations. Both are essential in Statistical Methods for Psychological Research-I, as they help researchers make sense of observations and test scientific hypotheses with precision and objectivity. Descriptive statistics refer to techniques used to organize, summarize, and describe the main features of a dataset. In psychological research, data are often collected from participants through tests, questionnaires, observations, or experiments. Raw data in their original form can be confusing and difficult to interpret. Descriptive statistics transform these raw scores into comprehensible summaries using measures of central tendency, measures of variability, and graphical representations. Measures of central tendency are used to identify the typical or average score in a distribution. The mean, median, and mode are the three primary measures. The mean is the arithmetic average of a set of scores and is widely used because it incorporates all values in the dataset. In psychological studies, the mean might represent the average anxiety score of a group or the average reaction time in a cognitive experiment. The median is the middle value in an ordered distribution and is particularly useful when data are skewed or contain extreme scores. The mode is the most frequently occurring score and is helpful in identifying common responses or patterns, especially in categorical data. Each measure provides different insights, and the choice depends on the nature and distribution of the data. Measures of variability, also known as measures of dispersion, describe the spread or distribution of scores around the central value. In psychology, variability is crucial because it reflects individual differences. The range, variance, and standard deviation are commonly used indicators. The range is the difference between the highest and lowest scores, offering a simple measure of spread. Variance represents the average squared deviation from the mean, while the standard deviation is the square root