Detection of irrelevant data can be a difficult task, as it depends on the context and domain of your data science project. Exploratory data analysis, data profiling, and domain knowledge are all methods that can help in this process. Exploratory data analysis involves using descriptive statistics, visualizations, and summary tables to get a sense of the data and its characteristics, such as outliers, anomalies, missing values, inconsistencies, and patterns. Data profiling examines the structure, content, and quality of your data using metadata such as data types, formats, lengths, ranges, frequencies, and distributions. You can use tools or libraries to automate this process and generate reports that can highlight potential issues with the data. Domain knowledge involves using your expertise and experience in the field or subject matter of your data to evaluate its relevance and validity. Consulting with domain experts or stakeholders can also provide insight into their expectations for the data and analysis.