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:

• 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 = Average or Mean = /n Median

– Value of 50th percentile, half of values fall above, half below

Maximum, Minimum, Range (Max-Min) Mode - most common value Standard deviation Variance (SD

2)

Analyze these data...

Mean, max, min, range, median, mode

• 18

• 33

• 4

• 47

• 49

• 38

• 29

• 4

• 55

sample size (n) Mode Sum

mean=average=/n median = halfway Variance =(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: One Step at a Time

Change a Value: Repeat the Calculations you Defined

Spreadsheets

Spreadsheets are tables

Spreadsheets allow calculations and manipulations of data

• Calculations: mean, standard deviation

• Manipulations: sort,

• Visualizations: plot, pie chart

CostaRica Nicaragua Rainforest 625,000 3,712,000 Dry Forest 50,000 300,000

Total 675,000 4,012,000

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 # Length Velocity Age

1

2

3

4

5

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