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Data and Statistics. Chapter 1 BA 201 – Fall 2010. Statistics. Numerical facts such as averages, medians, percents, and index numbers. Art and science of collecting, analyzing, presenting, and interpreting data. . Data and Data Sets.

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Data and statistics

Data and Statistics

Chapter 1

BA 201 – Fall 2010


Statistics
Statistics

  • Numerical facts such as averages, medians, percents, and index numbers.

  • Art and science of collecting, analyzing, presenting, and interpreting data.


Data and data sets
Data and Data Sets

  • Data are the facts and figures collected, analyzed, and summarized for presentation and interpretation.

  • The data set is all the data collected in a particular study.


Elements variables and observations
Elements, Variables, and Observations

  • Elements are the entities on which data are collected.

  • A variable is a characteristic of interest for the elements.

  • An observation is the set of measurements obtained for a particular element.


Data Sets, Elements, Variables, and Observations

Variables

Observation

Elements

Stock Annual Earn/

Exchange Sales($M) Share($)

NQ 73.10 0.86

N 74.00 1.67

N 365.70 0.86

NQ 111.40 0.33

N 17.60 0.13

Dataram

EnergySouth

Keystone

LandCare

Psychemedics

N 74.00 1.67

Data Set


Scales of measurement
Scales of Measurement

Nominal

Ordinal

Interval

Ratio


Scales of measurement1
Scales of Measurement

  • Nominal – labels or names.

    • E.g., CoB, CoST, CoAL, CoH; male or female; department 1, 2, 3, 4, …

  • Ordinal - have the properties of nominal data and the order or rank of the data is meaningful.

    • E.g., Freshman, Sophomore, Junior, or Senior


Scales of measurement2
Scales of Measurement

  • Interval – have the properties of ordinal data, and the interval between observations is expressed in terms of a fixed unit of measure.

    • E.g., ACT score of 23, 24, 25, …; years.

    • Numeric

  • Ratio - have all the properties of interval data and the ratio of two values is meaningful.

    • E.g., 30 credit hours versus 120 credit hours

    • Must include zero


What you can do with scales
What You Can Do With Scales

http://www.graphpad.com/faq/viewfaq.cfm?faq=1089


Categorical or quantitative data
Categorical or Quantitative Data

Categorical (or Qualitative)

Quantitative

How much or how many

Numeric

Interval or ratio

More statistical tests available

  • Grouped by categories

  • Numeric or non-numeric

  • Nominal or ordinal


Scales of Measurement

Data

Categorical

Quantitative

Numeric

Numeric

Non-numeric

Nominal

Ordinal

Nominal

Ordinal

Interval

Ratio


Cross sectional or time series data
Cross-Sectional or Time Series Data

  • Cross-sectional data are collected at the same or approximately the same point in time.

    • E.g., Building permits in January

  • Time series data are collected over several time periods.

    • E.g., Building permits each month


Data sources
Data Sources

  • Existing Sources – data already exists.

  • Statistical Studies – data obtained through a study.

    • Experimental Studies – variable of interest identified and other variables controlled.

    • Observational studies – no attempt is made to control or influence the variables of interest.


Descriptive statistics
Descriptive Statistics

  • Data summarized and presented in a form that is easy for the reader to understand.

  • Tabular, graphical, or numerical.

Average

Tune-up

= $79


Statistical inference
Statistical Inference

  • Use data from a sample to make estimates or test hypotheses about a population.


Statistical inference1
Statistical Inference

  • Population – set of all elements in a particular study.

    • Census – collects data about entire population.

  • Sample – a subset of the population.

    • Sample survey – collects data for a sample.


Statistical inference2
Statistical Inference

Population

Sample

Statistics about sample

Statistics about the sample provide an estimate of the population.


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