Post #2575

✅Data Analyst Interview Questions with Answers: Part-8 71. What is Power BI or Tableau used for? Power BI and Tableau are Business Intelligence (BI) tools that convert raw data into interactive dashboards and reports. They help you connect to multiple data sources, clean and transform data, create visuals, and share insights with stakeholders. Example: A company connects its sales database to Power BI and builds a dashboard showing revenue trends, top products, and customer performance. 👉 Power BI and Tableau help organizations transform raw data into interactive visual insights for decision-making. 72. What is a data model? A data model defines how tables are connected using relationships, combining multiple tables for accurate analysis and improved dashboard performance. Example: Orders Table → Customer Table → Product Table (all connected using IDs). 👉 A data model organizes relationships between tables to enable accurate reporting. 73. What is a relationship? A relationship connects tables using a common column, with types like one-to-many, many-to-many, and one-to-one. Example: One customer → many orders (Customer_ID links Customers table to Orders table). 👉 Proper relationships prevent duplicate results and incorrect calculations. 74. What is DAX? DAX (Data Analysis Expressions) is a formula language used in Power BI for calculations, creating measures, time-based calculations, and business logic. Example: Total Sales = SUM(Sales[Amount]), YTD Sales = TOTALYTD(SUM(Sales[Amount]), Sales[Date]). 👉 DAX helps create advanced calculations and business metrics in Power BI. 75. Difference between measure and calculated column? Calculated columns are calculated row by row, stored in tables, and use memory. Measures are calculated dynamically, used in visuals, and more efficient. Example: Calculated column (Profit = Sales[Revenue] - Sales[Cost]), Measure (Total Profit = SUM(Sales[Revenue]) - SUM(Sales[Cost])). 👉 Measures are preferred for performance optimization. 76. What is Power Query? Power Query is a data transformation tool used before data enters Power BI, for cleaning, removing duplicates, changing data types, and more. Example: Converting text date into proper date format before building dashboard. 👉 Power Query prepares raw data for analysis. 77. What are filters and slicers? Filters restrict data in visuals or pages, while slicers are interactive filters visible to users. Example: A slicer allows users to select Region or Product to change dashboard view. 👉 Slicers improve user interaction and dashboard flexibility. 78. What is row-level security (RLS)? RLS restricts data visibility based on user roles, protecting sensitive data and enabling multi-user dashboards. Example: Sales manager sees only their region, HR sees only employee data. 👉 RLS ensures users only access authorized data. 79. What is refresh schedule? Refresh schedule automatically updates dashboard data, with options for manual, scheduled, or real-time refresh. Example: Daily sales dashboard updates every morning at 8 AM. 👉 Refresh schedules ensure dashboards always show updated data. 80. How do you optimize reports? Optimization techniques include removing unnecessary columns, using measures instead of calculated columns, avoiding too many visuals, and using star schema data models. Example: Replacing multiple calculated columns with one measure improves performance. 👉 Optimized reports improve speed, performance, and user experience. Double Tap ♥️ For Part-8