Tiêu đề 2nd stats ch 03.pdf ✅

Chapter 3 Time Series One and Two Marks Questions and Answers Question 1. Define time series/what is time-series? Give an example Answer: • A set of figures relating to a variable according to a time is called Time series OR chronological arrangements of the statistical data is called Time series • Production of a firm arranged from the year 2000 to 2008, Sales statistics of a certain article for the year 1998 to 2005. Question 2. What do you meant by trend? Answer: Trend is the overall change taking place in the series of the data over a given period. Question 3. What do you mean by Secular trend / Seasonal variation / cyclical variation / Irregular variations? Answer: • Secular trend/Trend refers to the tendency of the variable to increase, decrease, or remain steady over a given period. • Seasonal variations refer to the variations caused annually by the seasons of the year. Also includes the variations of any kind which are periodic in nature and whose period is shorter than one year. ( t < 1 year) • Cyclical variations are fluctuations spread over a period of more than one year. Most of the Time series relating to Economics and Business show some kind of cyclical variations. Cyclical variation is an oscillatory variation, which occurs in four stages, such as (1) Prosperity (2) Decline (3) Depression and (4) Improvement. • Irregular / Erratic variations are those changes of time series, which are irregular in nature and do not show any pattern. The causes of irregular

Chapter 3 Time Series Question 8. What are the stages/Phases of a cyclical trend/Business cycle? Answer: (1) Prosperity (2) Decline (3) Depression and (4) Improvement. Question 9. Which components of time series are applicable in case of Answer: 1. Fire accident in a factory 2. Increase of woolen goods during winter 3. Fall in the death rate due to advances in Science 4. An era of Prosperity 5. An increase in employment during harvest season. – (1) Random, (2) Seasonal, (3) Secular, (4) Cyclical variations (5) Seasonal variation Question 10. With which components of a time series would you mainly associated each of the following? (a) Increase in money in circulation for the last 10 years (b) Rain fall in Bangalore that occurred for a week in December 2007. Answer: (a) Secular trend (b) Irregular variations Question 11. Mention the type of component (T-S) seen in the following : “Increase in the number of deaths of piligrims due to floods and landslides in the Uttarkhand recently” Answer: Irregular variations Question 12. What is the name given to the line, which is obtained under method of least squares? Answer: Linear/Straight line trend/line
Chapter 3 Time Series Question 13. What is a Historigram? /Name the graph of time series. Answer: The graph of time series is called Historigram. Question 14. Give any two uses of Analysis of Time Series. Answer: Analysis of Time series helps to understand the past behavior of the data / to predict the future trend. Question 15. What is the duration of seasonal variation? Answer: Within one year (t < 1 year) Question 16. Mention the conditions to be followed in the method of least squares. /Principles of Method of least squares. Answer: The sum of the deviations obtained from the actual and trend values is Zero ie. Σ(Y – Ȳ)=0 and The sum of the squares of the deviations obtained from the actual and trend values is least. i.e., Σ(Y – Ȳ) 2 is least Question 17. What do you mean by moving averages? Answer: Moving averages are the averages obtained by finding the arithmetic means of successive values of the time series by taking say 3/4/5 years at a time by leaving the first and adding the next; this is to eliminate short-term variations/fluctuations that are present in the time series. Question 18. Write any merit and demerit of moving average methods. Answer: The merit is it is simple and easy; Demerit is that, not all trend values can be obtained by this method