Statistics 1 Marks Each

The method of moving averages is very useful to find trend by eliminating the effect of short term variation.

The components of time series are :

• Long-term component or trend
• Seasonal component
• Cyclical component
• Random or Irregular component ’

The effect of seasonal component indicates fluctuations repeating within one year.

Trend is an important component of time series.

• Following are the methods to estimate it :
• Graphical Method
• Method of Least Squares
• Method of Moving Averages

The method of drawing inferences on different characteristics of time series by analysis of time series data is called time series analysis.

The statistical data collected at specific intervals of time and arranged in a chronological order is called time series.

Unemployment in developed country, production coal mines, new medicines, inventions in medical fields, decrease in child death rate, these are the example of time series having decreasing trend.

If the period of moving average is an even number, it becomes difficult to use moving average method to find trend.

When the trend is to be obtained after eliminating the effect of short-term variations, then the method of moving average is useful.

When the trend of the time series is non-linear, the method of least squares of fitting the trend line cannot be useful.

The components taking place in the variable quantity of the time series at a fixed period of time in the year say, winter, summer, monsoon are called the seasonal component.

Trend of the time series is an important component to take decesion regarding economic policy.

In the time series, time t is a discrete variable while the variable y may be discrete or continuous variable.

In the graphical method the points are joined serially by line segments.

The graphical method is the easiest method to find trend.

The error arises in estimated values due to irregular component.

The cycles of booms and recessions appeared in business activities is the illustration of cyclical component.

The business or trade cycle arises due to cyclical component

The duration of oscillation of seasonal components is less than one year.

The long-term component is obtained by eliminating short-term and irregular components from to total variation of a time series

The seasonal and cyclical components are recognised by short-term components as other

The variation seen in the variable of a time series over a very long period of time is called long-term component.

The component obtained by eliminating trend, seasonal component and cyclical component from the variable

The mathematical and exact method of finding trend of a time series is ‘Least square’ method

The analysis of time series is necessary to forecast the future estimates.

Seasonal and cyclical components are such that their periods of oscillation are almost regular.

The components whose period of oscillation is almost certain are called regular components

The short-term component is not considered in trend.

The trend in the time series having almost continuous increase or decrease is called a linear trend.

Long-term component is recognised by trend as other name.

The analysis of time series becomes useful in business, sciences and social-political field.

Due to uncertainity in business-commerce, the data collected by a time series are more important.

The data regarding changes in a variable at specific interval are given by time series.

At present time series is widely used in different methods of business analysis.

The forecasts are useful for future planning.

If the inference based on the study of the past phenomena is made for some specified point of time of the future, then it is called forecast.

The fixed time period during which the regularity of variations in the time series is observed, is called the duration of oscillation.

The fluctuations which prevail on the time series for a long period of time is called long term fluctuations or trend.