Welcome to my Introduction to Economic Statistics Class

 

In the event you found my webpage accidentally, here is some useful information regarding the assigned text by the

Economics Department for the class [ECON 380]

Required text:  Statistics for Management and Economics (8th Edition) Selected Chapters for CSU Long Beach

         Author:  Gerald Keller

           ISBN:   0-324-66869-4 

                      This is a special order of  the student version of the text (at a reduced price) for the CSULB

                     students. It is a paperback edition with a lower price than the regular text, although still not a cheap one.

                     If you can find used copies of the student edition on the internet with a reasonable price, you can buy them.

 

Note :   The ISBN number for the regular student text is 03-245-6959 which has a higher price. So, if you plan to purchase

              your  text on  the internet, make sure that you order the student edition.

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My phone number is (562) 985-5079 where you can leave a voice message for me or you can email me at  cglezako@csulb.edu                                if you need to come in contact with me.

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                                                                  TYPES  OF  DATA

 

As has been stated, one of the objectives of Statistics is to obtain information from analyzing the available data. There are different types of data and before one embarks into data analysis, it is advisable to examine and define the different types of data measurements.

Measurement: is the process of assigning numbers or descriptors to observations, that is, the process of assigning values to a variable:

Variable: is an entity that varies or an entity that assumes different values (e.g., prices,  grades, income, age, time, etc. )

Constant: is an entity that remains the same or unchanged in a given context. (sales tax rate, depreciation coefficient, etc.)

There are two types of variables, discrete and continuous.

Data Scales: There are four scales for data.                                   DATA

                                                                                 Discrete    /                  \  Conitinuous

  1. Nominal                                                       Nominal                         Interval
  2. Ordinal                                                         Ordinal                           Ratio
  3. Interval and                                                  Interval
  4. Ratio                                                             Ratio

Furthermore, economic data come in three different forms:

  1. Time Series: are data that represent the values of a variable arranged chronologically or over a given period of time.
  2.  Cross Section: are data that  represent the values of a variable at a given point of time classified under a certain criterion.
  3. Panel data: are a combination of the previous two types, that is, they are data representing the values of several categories of a variable over time. In other words, panel data is a set of data representing the various categories of a variable observed over multiple time periods.

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                                                                          NEW  TERMS

Population     Sample

Parameter: is a measure of a population characteristic

Statistic or Estimator: is a measure of a sample characteristic (also defined as a “function  of the sample values”)

Estimate: Is a specific value of an estimator ( average test score of a given class = 82.6 )

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                                              GRAPHIC PRESENTATION OF STATISTICAL DATA

 Another method of presenting statistical data in addition to numeric tables is by using graphs.

A graph or a chart is a pictorial expression of the information of a given set of data. A great variety of charts has been used in statistical studies. There is no single rule that can be used to guide one regarding the choice of the most effective or appropriate chart type.

It is true that a picture is worth a thousand words. However, one should point out that graphs or charts provide the reader only with an approximate value of the desired information. If one would like to have exact or accurate information, he should refer to the original data source.

The most common types of charts for economic/business data are:

  1.  Line Chart or the Arithmetic Line diagram.
  2.  Bar chart
  3.  Component-Part chart or Pie chart.
  4.  Pictogram or Pictograph
  5. Histogram

The line chart consists of a line representing usually data over time (time series data). Attention should be paid to the type of time series data one is using to construct the line chart: Period data or Point data. For period data one should use (vertical) guide lines at the point of the beginning and end of the period (Year, Quarter, Month) but plot the quantity (sales, exports, enrolment, output) in the middle of the period. However, for the point data, the (vertical) guideline and quantities (daily temperatures or gas prices, end of year cash on hand) should be plotted at the specific points.

For comparison purposes, one can use more than one lines to represent different variables over the same time period.

The bar chart  is a graph consisting of a group of rectangular bars the height of which represents a given quantity with the units measured on the perpendicular (reference) axis. The width of each bar is not of any importance, but all bars must be of equal width. The bar charts can be used with both, time series and cross section data. Also bar charts can be horizontal or vertical.

The Component Part chart shows the relationships among individual parts as well as of the totals of several sets of data. The relationships can be expressed in either the actual amounts of the data or in percentages that is, their relative values. The most common ways for showing component part charts are bars or segments of a circle called pie chart.

A Pictogram or Pictograph  consists of a number of symbols or pictures of the same size each representing a certain magnitude of the item shown, e.g., a barrel, TV set, car, etc. The presentation of statistical information by a picture is useful in stimulating the reader’s interest  and for showing the data to the layman in a self-explanatory fashion.

In order to explain the use of histograms, one must first understand the concept of frequency distribution which is the next topic.