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1 Data and Data Sets Data are the facts and figures collected, analyzed, and summarized for presentation and interpretation. All the data collected in a particular study are re to as the data set for the study.

1 1 Slide Data and Data Sets n Data are the facts and figures collected, analyzed, and summarized for presentation and interpretation. and summarized

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Page 1: 1 1 Slide Data and Data Sets n Data are the facts and figures collected, analyzed, and summarized for presentation and interpretation. and summarized

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Data and Data Sets

Data are the facts and figures collected, analyzed,

and summarized for presentation and interpretation. All the data collected in a particular study are referred

to as the data set for the study.

Page 2: 1 1 Slide Data and Data Sets n Data are the facts and figures collected, analyzed, and summarized for presentation and interpretation. and summarized

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Stock Annual Earn/Exchange Sales($M) Share($)

Data, Data Sets, Elements, Variables, and Observations

Company

Dataram EnergySouth Keystone LandCare Psychemedics

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

Variables

Element

Names

Data Set

Observation

Page 3: 1 1 Slide Data and Data Sets n Data are the facts and figures collected, analyzed, and summarized for presentation and interpretation. and summarized

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Data can be further classified as being qualitative or quantitative. Data can be further classified as being qualitative or quantitative.

The statistical analysis that is appropriate depends on whether the data for the variable are qualitative or quantitative.

The statistical analysis that is appropriate depends on whether the data for the variable are qualitative or quantitative.

In general, there are more alternatives for statistical analysis when the data are quantitative. In general, there are more alternatives for statistical analysis when the data are quantitative.

Qualitative and Quantitative Data

Page 4: 1 1 Slide Data and Data Sets n Data are the facts and figures collected, analyzed, and summarized for presentation and interpretation. and summarized

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Qualitative Data

Labels or names used to identify an attribute of each element Labels or names used to identify an attribute of each element

Often referred to as categorical data Often referred to as categorical data

Use either the nominal or ordinal scale of measurement Use either the nominal or ordinal scale of measurement

Can be either numeric or nonnumeric Can be either numeric or nonnumeric

Appropriate statistical analyses are rather limited Appropriate statistical analyses are rather limited

Page 5: 1 1 Slide Data and Data Sets n Data are the facts and figures collected, analyzed, and summarized for presentation and interpretation. and summarized

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Quantitative Data

Quantitative data indicate how many or how much: Quantitative data indicate how many or how much:

discrete, if measuring how many discrete, if measuring how many

continuous, if measuring how much continuous, if measuring how much

Quantitative data are always numeric. Quantitative data are always numeric.

Ordinary arithmetic operations are meaningful for quantitative data. Ordinary arithmetic operations are meaningful for quantitative data.

Page 6: 1 1 Slide Data and Data Sets n Data are the facts and figures collected, analyzed, and summarized for presentation and interpretation. and summarized

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Descriptive Statistics

Most of the statistical information in newspapers, magazines, company reports, and other publications consists of data that are summarized and presented in a form that is easy to understand. Such summaries of data, which may be tabular, graphical, or numerical, are referred to as descriptive statistics.

Page 7: 1 1 Slide Data and Data Sets n Data are the facts and figures collected, analyzed, and summarized for presentation and interpretation. and summarized

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Example: Hudson Auto Repair

The manager of Hudson Autowould like to have a betterunderstanding of the costof parts used in the enginetune-ups performed in theshop. She examines 50customer invoices for tune-ups. The costs of

parts,rounded to the nearest dollar, are listed on the

nextslide.

Page 8: 1 1 Slide Data and Data Sets n Data are the facts and figures collected, analyzed, and summarized for presentation and interpretation. and summarized

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Example: Hudson Auto Repair

Sample of Parts Cost ($) for 50 Tune-ups

91 78 93 57 75 52 99 80 97 6271 69 72 89 66 75 79 75 72 76104 74 62 68 97 105 77 65 80 10985 97 88 68 83 68 71 69 67 7462 82 98 101 79 105 79 69 62 73

91 78 93 57 75 52 99 80 97 6271 69 72 89 66 75 79 75 72 76104 74 62 68 97 105 77 65 80 10985 97 88 68 83 68 71 69 67 7462 82 98 101 79 105 79 69 62 73

Page 9: 1 1 Slide Data and Data Sets n Data are the facts and figures collected, analyzed, and summarized for presentation and interpretation. and summarized

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Tabular Summary: Frequency and Percent Frequency

50-59 60-69 70-79 80-89 90-99 100-109

2 13 16 7 7 5 50

4 26 32 14 14 10 100

(2/50)100(2/50)100

Parts Cost ($)

Parts Frequency

PercentFrequency

Page 10: 1 1 Slide Data and Data Sets n Data are the facts and figures collected, analyzed, and summarized for presentation and interpretation. and summarized

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Graphical Summary: Histogram

22

44

66

88

1010

1212

1414

1616

1818

PartsCost ($) PartsCost ($)

Fre

qu

en

cy

Fre

qu

en

cy

50-59 60-69 70-79 80-89 90-99 100-11050-59 60-69 70-79 80-89 90-99 100-110

Tune-up Parts CostTune-up Parts Cost

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Numerical Descriptive Statistics

Hudson’s average cost of parts, based on the 50 tune-ups studied, is $79 (found by summing the 50 cost values and then dividing by 50).

The most common numerical descriptive statistic is the average (or mean).

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Statistical Inference

PopulationPopulation

SampleSample

Statistical inferenceStatistical inference

CensusCensus

Sample surveySample survey

- the set of all elements of interest in a particular study

- a subset of the population

- the process of using data obtained from a sample to make estimates and test hypotheses about the characteristics of a population

- collecting data for a population

- collecting data for a sample

Page 13: 1 1 Slide Data and Data Sets n Data are the facts and figures collected, analyzed, and summarized for presentation and interpretation. and summarized

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Process of Statistical Inference

1. Population consists of all

tune-ups. Averagecost of parts is

unknown.

1. Population consists of all

tune-ups. Averagecost of parts is

unknown.

2. A sample of 50engine tune-ups

is examined.

2. A sample of 50engine tune-ups

is examined.

3. The sample data provide a sample

average parts costof $79 per tune-up.

3. The sample data provide a sample

average parts costof $79 per tune-up.

4. The sample averageis used to estimate the population average.

4. The sample averageis used to estimate the population average.

Page 14: 1 1 Slide Data and Data Sets n Data are the facts and figures collected, analyzed, and summarized for presentation and interpretation. and summarized

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Statistical Analysis Using Microsoft Excel

Statistical analysis typically involves working with large amounts of data. Computer software is typically used to conduct the analysis. Frequently the data that is to be analyzed resides in a spreadsheet.

Modern spreadsheet packages are capable of data management, analysis, and presentation. MS Excel is the most widely available spreadsheet software in business organizations.

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Statistical Analysis Using Microsoft Excel

3 tasks might be needed:• Enter Data

• Enter Functions and Formulas• Apply Tools

A

1Parts Cost

2 913 714 1045 856 627 788 69

D EMean =AVERAGE(A2:A71)

Median =MEDIAN(A2:A71)Mode =MODE(A2:A71)

Range =MAX(A2:A71)-MIN(A2:A71)

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Excel Worksheet (showing data)

Note: Rows 10-51 are not shown.

Statistical Analysis Using Microsoft Excel

A B C D

1 Customer Invoice #Parts

Cost ($)Labor

Cost ($)2 Sam Abrams 20994 91 1853 Mary Gagnon 21003 71 2054 Ted Dunn 21010 104 1925 ABC Appliances 21094 85 1786 Harry Morgan 21116 62 2427 Sara Morehead 21155 78 1488 Vista Travel, Inc. 21172 69 1659 John Williams 21198 74 190

A B C D

1 Customer Invoice #Parts

Cost ($)Labor

Cost ($)2 Sam Abrams 20994 91 1853 Mary Gagnon 21003 71 2054 Ted Dunn 21010 104 1925 ABC Appliances 21094 85 1786 Harry Morgan 21116 62 2427 Sara Morehead 21155 78 1488 Vista Travel, Inc. 21172 69 1659 John Williams 21198 74 190

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Excel Formula Worksheet

Note: Columns A-B and rows 10-51 are not shown.

Statistical Analysis Using Microsoft Excel

C D E F G

1Parts

Cost ($)Labor

Cost ($)2 91 185 Average Parts Cost =AVERAGE(C2:C51)3 71 2054 104 1925 85 1786 62 2427 78 1488 69 1659 74 190

C D E F G

1Parts

Cost ($)Labor

Cost ($)2 91 185 Average Parts Cost =AVERAGE(C2:C51)3 71 2054 104 1925 85 1786 62 2427 78 1488 69 1659 74 190

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Excel Value Worksheet

Note: Columns A-B and rows 10-51 are not shown.

Statistical Analysis Using Microsoft Excel

C D E F G

1Parts

Cost ($)Labor

Cost ($)2 91 185 Average Parts Cost 793 71 2054 104 1925 85 1786 62 2427 78 1488 69 1659 74 190

C D E F G

1Parts

Cost ($)Labor

Cost ($)2 91 185 Average Parts Cost 793 71 2054 104 1925 85 1786 62 2427 78 1488 69 1659 74 190

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A frequency distribution is a tabular summary of data showing the frequency (or number) of items in each of several non-overlapping classes.

A frequency distribution is a tabular summary of data showing the frequency (or number) of items in each of several non-overlapping classes.

The objective is to provide insights about the data that cannot be quickly obtained by looking only at the original data.

The objective is to provide insights about the data that cannot be quickly obtained by looking only at the original data.

Ch. 2: Summarizing Qualitative DataFrequency Distribution

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Guests staying at Marada Inn were asked to rate the

quality of their accommodations as being excellent,

above average, average, below average, or poor. The

ratings provided by a sample of 20 guests are: Above Average Below Average Above Average Average Average Above Average Above Average

Average Above Average Below Average Poor Excellent Above Average Average

Above Average Above Average Below Average Poor Above Average Average

Frequency Distribution

Example: Marada Inn

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Frequency Distribution

PoorBelow AverageAverageAbove AverageExcellent

2 3 5 9 1

Total 20

Rating Frequency

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Using Excel’s COUNTIF Functionto Construct a Frequency Distribution

Excel Formula Worksheet

Note: Rows 9-21 are not shown.

A B C D1 Quality Rating Quality Rating Frequency2 Above Average Poor =COUNTIF($A$2:$A$21,C2)3 Below Average Below Average =COUNTIF($A$2:$A$21,C3)4 Above Average Average =COUNTIF($A$2:$A$21,C4)5 Average Above Average =COUNTIF($A$2:$A$21,C5)6 Average Excellent =COUNTIF($A$2:$A$21,C6)7 Above Average Total =SUM(D2:D6)8 Above Average

Download Ch01-Ch02-CustomerRatings.xlsx

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Excel Value Worksheet

Using Excel’s COUNTIF Functionto Construct a Frequency Distribution

Note: Rows 9-21 are not shown.

A B C D1 Quality Rating Quality Rating Frequency2 Above Average Poor 23 Below Average Below Average 34 Above Average Average 55 Average Above Average 96 Average Excellent 17 Above Average Total 208 Above Average

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The relative frequency of a class is the fraction or proportion of the total number of data items belonging to the class.

The relative frequency of a class is the fraction or proportion of the total number of data items belonging to the class.

A relative frequency distribution is a tabular summary of a set of data showing the relative frequency for each class.

A relative frequency distribution is a tabular summary of a set of data showing the relative frequency for each class.

Relative Frequency Distribution

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Percent Frequency Distribution

The percent frequency of a class is the relative frequency multiplied by 100. The percent frequency of a class is the relative frequency multiplied by 100.

A percent frequency distribution is a tabular summary of a set of data showing the percent frequency for each class.

A percent frequency distribution is a tabular summary of a set of data showing the percent frequency for each class.

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Relative Frequency andPercent Frequency Distributions

PoorBelow AverageAverageAbove AverageExcellent

.10 .15 .25 .45 .05

Total 1.00

10 15 25 45 5 100

RelativeFrequency

PercentFrequencyRating

.10(100) = 10

.10(100) = 10

1/20 = .051/20 = .05

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Excel Formula Worksheet

Note: Columns A-B and rows 9-21 and are not shown.

Using Excel to Construct Relative Frequency and Percent Frequency

Distributions

C D E F

1 Quality Rating FrequencyRelative

FrequencyPercent

Frequency2 Poor =COUNTIF($A$2:$A$21,C2) =D2/$D$7 =E2*1003 Below Average =COUNTIF($A$2:$A$21,C3) =D3/$D$7 =E3*1004 Average =COUNTIF($A$2:$A$21,C4) =D4/$D$7 =E4*1005 Above Average =COUNTIF($A$2:$A$21,C5) =D5/$D$7 =E5*1006 Excellent =COUNTIF($A$2:$A$21,C6) =D6/$D$7 =E6*1007 Total =SUM(D2:D6) =SUM(E2:E6) =SUM(F2:F6)8

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Excel Value Worksheet

Using Excel to Construct Relative Frequency and Percent Frequency

Distributions

C D E F

1 Quality Rating FrequencyRelative

FrequencyPercent

Frequency2 Poor 2 0.10 103 Below Average 3 0.15 154 Average 5 0.25 255 Above Average 9 0.45 456 Excellent 1 0.05 57 Total 20 1.00 1008

Note: Columns A-B and rows 9-21 and are not shown.