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AAEC 4302 ADVANCED STATISTICAL METHODS IN AGRICULTURAL RESEARCH

AAEC 4302 ADVANCED STATISTICAL METHODS IN AGRICULTURAL RESEARCH. Economic Data: Chapter 2. Data, Observation and Variables. Data are the quantitative or qualitative facts or information used for statistical analysis

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AAEC 4302 ADVANCED STATISTICAL METHODS IN AGRICULTURAL RESEARCH

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  1. AAEC 4302ADVANCED STATISTICAL METHODS IN AGRICULTURAL RESEARCH Economic Data: Chapter 2

  2. Data, Observation and Variables • Data are the quantitative or qualitative facts or information used for statistical analysis • The cases or instances that make up the data about any economic/biological process are called observations

  3. Data, Observation and Variables • A variable is a measurable characteristic of that process about which observations are collected • A data set is a collection of the observations on all the relevant variables for the analysis

  4. Data, Observation and Variables Observation Variables Number Y X1 X2 1 Y1 X11 X21 2 Y2 X12 X22 3 Y3 X13 X23 : : : : i Yi X1i X2i : : : : n Yn X1n X2n

  5. Data, Observation and Variables • A discrete variable usually has integer values, which result from counting (example: number of people per household, age) • A continuous variable can take any real-number value, which usually result from more precise measurements (example: prices, income)

  6. Cross-Section and Time-Series Data • A cross-section data set contains a common set of variables, with (n) observations from a number of (n) entities (animals, persons, firms, states or nations) measured at about the same point in time

  7. Cross Section

  8. Cross Section Data set of 100 observations on 12 variables is the Survey of Financial Characteristics of Consumers in 1963: • Size The number of persons in the family • ED the number of years of education received by the head • AGE the age of the head, in years • EXP the labor market experience of the head, in years, calculated as EXP = AGE – ED – 5 • MONTHS the number of months during which the head worked • RACE the race of the head, coded 1 for whites and 2 for blacks • REG the region of residence, coded 1 for Northeast, 2 for North Central, 3 for South, and 4 for West • EARNS the wage and salary earnings of the head, expressed in thou of dollars • INCOME the total income of the family members, expressed in thou of dollars • WEALTH the wealth of the family on December 31, 1962, in thou of dol. • SAVINGS the savings of the family, in thou of dollars • ID the observation number, repeated as a variable for convenience Page 18 textbook

  9. Cross-Section and Time-Series Data • A time-series data set contains a common set of variables, with observations about a single entity in different periods of time

  10. Time series

  11. Time series Data set published in the Economic Report of the President 1982 contains following variables: • PGNP the implicit price deflator for gross national product, expressed as index numbers with PGNP = 100 for 1972 • GNP real gross national product (GNP), measured in billions of 1972 dollars • INV real gross private domestic investment, measured in billions of 1972 dollars • CON real personal consumption expenditures, measured in billions of 1972 dollars • DPI real disposable personal income, measured in billions of 1972 dollars • RINF1 the annual rate of inflation in the GNP deflator, % per annum • RINF2 the annual rate of inflation in the Consumer Price Index, % per annum • UPCT the unemployment rate, measured as a percent of the labor force • MI money supply, billions of dollars • RTB the interest rate on new issues of US Treasury Bills, % per annum • RAAA the interest yield of corporate bonds, % per annum • T time, measured as the number of years since 1955(i.e., 1 in 1956, 2 in 1957, etc.) Page 24 textbook

  12. Panel or Pooled Data • A panel or pooled data set is a cross-sectional data collected over a given time

  13. Change and growth in time series data • Absolute change or growth: Δ Yi = Yi – Yi-1 • Relative change is measured by the rate of change or the rate of growth: ri = Δ Yi / Yi-1 = Yi – Yi-1/ Yi-1= Yi / Yi-1 - 1

  14. Constructed Variables • Time series data base can have 4 types of adjustments to the data: • Index – measures the average of an underlying set of price or quantity variables in each year • Real terms - nominal values are adjusted • Annual rate of change of some other variable • Ratio of two other variables

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