Descriptive Analytics: Two Marks Important Questions and Answers

Python for Data Science

Chapter 4: Descriptive Analytics

Two Marks Questions with Answers

1. What are main facets of data ?

Answer: The facets of data can be structured data, unstructured data, natural language data, graph based data, audio‒video‒image data, streaming data.

2. What does data quality mean?

Answer: Data quality refers to the accuracy, completeness, consistency and reliability of data.

3. What are two main types of variables ?

Answer: The main types of variables are ‒ qualitative and quantitative.

4. G ive an example of categorical variables?

Answer: The examples of categorical variables are ‒ color, gender, city.

5. What are two subtypes of quantitative variables ?

Answer: The discrete and continuous variables are the subtypes of quantitative variables.

6. How can a numeric‒looking variable be categorical?

Answer: If numbers represent labels like "1= male, 2= female", they are categorical, not truly numerical.

7. What is statistical description of data ?

Answer: Statistical description of data is a process of using numbers, tables and graphs to describe and summerize the main features of a dataset.

8. What are two types of statistical measures?

Answer: Measures of central tendency and variability (dispersion).

9. What is frequency table ?

Answer: A frequency table is a way of organizing data to show how many times(frequency) each value or group of values occur in dataset.

10. Name two graphical tools for categorical data.

Answer: Bar charts and pie charts are most commonly used.

11. Which graphs are suitable for numerical data ?

Answer: Histograms, box plots and line graphs are ideal for quantitative data.

12. When is the median preferred over the mean?

Answer: When data contains outliers or is skewed, as the median is less affected by extreme values.

13. What is the significance of range and variance ?

Answer: Range ‒ Helps in weather forecasting and sports analytics to understand data variability, such as temperature differences or score variations.

Variance ‒ Used in risk assessment and finance to measure the dispersion of returns in investments.

14. What is standard deviation ?

Answer: It shows how much individual data points deviate from the mean on average.

15.  What is a normal distribution ?

Answer: It is a bell‒shaped, symmetric curve where most values cluster around the mean.

16. What are the properties of a normal curve ?

Answer: Mean = Median = Mode and total area under the curve equals 1.

17. What is a z‒score?

Answer: A z‒score measures how many standard deviations a data point is from the mean.

18. What does correlation measure?

Answer: The co‒relation measure represents the strength and direction of a linear relationship between two quantitative variables.

19. What is the range of the correlation coefficient (r) ?

Answer: It ranges from 1 to + 1, where ‒ 1 indicates perfect negative correlation and + 1 indicates perfect positive correlation.

20. What does r = 0 mean?

Answer: It means there is no linear relationship but a nonlinear relationship may still exist.

21. What does the slope (b) in regression indicate ?

Answer: It shows how much the dependent variable changes for a one‒unit change in the independent variable.

22. How is regression different from correlation ?

Answer: Correlation measures relationship strength, while regression provides a predictive model.