Page 256 - Touhpad Ai

7. A regression line that is calculated by least squares method will have an intercept and slope that
minimize the sum of the squared differences between the Y variable and the regression line.
8. A scatterplot is actually a graph of a curvilinear function.

9. The Y intercept of a regression line is equal to the value of X when Y is equal to zero.
10. If a regression line that was calculated by least squares method is plotted on a scatterplot,
all the points in the dataset should be on the line.

SECTION B (Subjective Type Questions)

A. Short answer type questions.
1. What is data modelling and why is it important?
Ans. Data modelling is the process of creating a plan or structure for how data is stored and connected in a
system. It is important because it helps in organizing data properly, making it easy to understand, manage,
and use across different departments.
2. How is data stored in a relational model?

Ans. In a relational model, data is stored in tables. Each table has rows and columns. Tables are linked through
a common field, like a student ID. This model helps keep data organised and reduces repetition.
3. What is the use of an ER (Entity-Relationship) diagram?
Ans. An ER diagram shows how different data items (called entities) are related to each other. It helps database
designers understand and plan the structure of the database before it is created, ensuring correct
relationships.

4. Explain the concept of dimensional data model with an example.
Ans. A dimensional model separates data into facts (like number of items sold) and dimensions (like date,
product, location). For example, 400 mobiles sold in Delhi in March uses facts and dimensions to make
data easy to analyse.
5. What is linear regression used for?
Ans. Linear regression is used to find a straight-line relationship between two variables. It helps in predicting the
value of one variable based on the other—for example, predicting marks based on study hours.
6. What is the regression called the line of best fit?

Ans. The line of best fit is a straight line drawn through data points in a scatter plot to show the trend. It helps in
predicting unknown values and minimising the distance between the line and actual data points.
7. How can regression be applied in real life?
Ans. Regression is used in real life to predict sales, weather, exam scores, and more. For example, a business
can predict future sales based on past data using a regression line.

8. How does dimensional modelling help in data analysis?
Ans. Dimensional modelling makes it easier and faster to analyse large amounts of data by organizing it into
facts and dimensions. It increases redundancy for better performance in reporting tools and business
intelligence systems.
9. If you were to design a student database, which model would you use and why?
Ans. A relational model would be best because student information like names, classes, and marks can be
stored in tables. These tables can be linked using a common ID, making the database organised and easy
to update.

254 Touchpad Artificial Intelligence - XI