Transcript Data and Spreadsheets

Data and Spreadsheet
Data and Spreadsheets
 What are data?
 What are statistics?
 What are spreadsheets?
 How can you analyze data with
spreadsheets?
Data
 Data are pieces of information that can define
subjects
 Data can be numbers, words, descriptions
 The word data is PLURAL, datum is singular
 Example of Data about George:
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Age: 57.2 (years)
43rd President
Male
Favorite letter: W
Favorite words: Bring them on.
Types of Data
 Numbers – two types
– Real #s – rational numbers – 57 years
– Integers – whole numbers – 170 lbs
 Letters – called characters in programming
– W is a character
 Words – called strings in programming
– “Bring them on” is a strings, can be individual words or
phrases
 Other : Image, Sound…
Statistics and Data
 Test Scores:
– Jeff: 88
– Mollie: 92
– Marcie: 88
– Dave: 47
– Karim: 99
– Willoughby: 6
– Benjamin: 0
 What statistics can you
calculate to describe
these data?
– Try to think of four
things to describe the
data
 stop
Statistics
 Statistics are derived from the data
 Statistics are descriptions of data
 Statistics are meant to simplify the data
 Statistics can be misleading
Typical Statistics
 Sample Size - number of individuals measured = n
 Sum = S
 Average or Mean = S/n
 Median
– Value of 50th percentile, half of values fall above, half below
 Maximum, Minimum, Range (Max-Min)
 Mode - most common value
 Standard deviation
2
 Variance (SD )
Analyze these data...
 Mean, max, min,
 sample size (n)
range, median, mode  Mode
• 18
 Sum S
• 33
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4
47
49
38
29
4
55
 mean=average=S/n
 median = halfway
 Variance =S(x-mean)2/n
Calculators Compared with
Spreadsheets
Calculators
Spreadsheets
Single Calculation
Many Interrelated
Calculations at Once
Built-in Math
Operators
Built-in and customized
Math Operation
Complex Calculations: Change a Value: Repeat
One Step at a Time
the Calculations you
Defined
Spreadsheets
 Spreadsheets are tables
Rainforest
Dry Forest
Total
CostaRica Nicaragua
625,000 3,712,000
50,000
300,000
675,000
4,012,000
 Spreadsheets allow calculations and
manipulations of data
• Calculations: mean, standard deviation
• Manipulations: sort,
• Visualizations: plot, pie chart
Spreadsheet Design Questions
 What numbers are you starting with?
 What numbers do you need to calculate?
 What are the relationships among the
numbers to perform these calculations?
 What text do you need to make the
spreadsheet clear to yourself and other
people?
Make a data table:
 Fly 1, length 13.4 mm, velocity 27 Kph, age 21 days
 Fly 2, length 9.4 mm, velocity 0 Kph, age 220 days
 Fly 3, length 9.3 mm, velocity 44 Kph, age 1 days
 Fly 4, length 13.4 mm, velocity 17 Kph, age 32 days
 Fly 5, length 17.4 mm, velocity 33 Kph, age 11 days
 How many columns?
 How many rows?
 #s go down or across?
Data Table
Fly #
1
2
3
4
5
Length
Velocity
Age
Microsoft Excel
 Typical spreadsheet program
– VisiCalc is original commercial spreadsheet
– Lotus 1-2-3 took over in the 1980s.
 Has similar controls to MS Word
 Now allows graphing (charts)
 Excel tables and graphs can be copied into
MS Word
Excel Basic
 Data are stored in cells.
 Cells are name by Letters and numbers e.g.
A12. This is also called cell reference.
 Cells can hold number, text, image, and
most important thing: Formula.
 Formulas are started with a “=” sign. It can
be any mathematical operations.
Relative Cell Reference
Absolute Cell reference
Friday’s Assignment
 We will work with Microsoft Excel to
analyze some data
 Groups of two will submit one finished
spreadsheet for the assignment