Collecting data. stat 480 Heike Hofmann

Transcription

1 Collecting data stat 480 Heike Hofmann

2 Salaries...economics..financial.data Health...fitness Movies..e.g..ratings..box.office.revenues... Global.issues..comparison.across.countries Favorite Like it very much Like it Don't like it that much Health...diseasesTraveling..e.g..flight.delays..tarmac.waits..airport.performance... Sports..e.g..Baseball..Football... Crime.Data..e.g..FBI.Database. Favorite Like it very much Like it Don't like it that much Climate.Environment.Weather Environmental.Data..e.g..pollution..fuel.economy..CO2.emissions... Favorite Like it very much voting Like it Don't like it that much results count answer Don't like it that much Like it Like it very much Favorite

3 Outline Practice some of the skills you learned last time Two Scenarios of Data Collection vlookup Exercises Functions in Excel / Getting Help Discussing Data (problems)

4 Sheet formatting Excel is primarily an intermediate format between collection and analysis you will normally get it after data collection has taken place Want to optimize it for analysis

5 Data tidying Fill in all the blanks Give variables descriptive, but short, names Don t use any special characters, stick with numbers and letters Minimum of formatting

6 Your turn Tidy up the data provided in file excel-tidy.xls

7 Data Collection

8 Scenario I Study in Human Perception Ability

9 How good is your Eyeballing? The eyeballing game tests your skills in completing a set of visual tasks Go to Play it once Copy results into Excel file & save for the next steps, see homework

10 Homework Now up on the website Two parts: - collect data from eyeballing game - small write-up Due next Thursday

11 Scenario II Basketball is after Baseball the sport with the highest salary pay for individual players. We can gather data on players salaries from online resources (e.g. HoopsHype, ESPN, USAToday s database).

12 Your Turn Go to the HoopsHype salary database at Select one team and one season, get salary information for all players on the team. Copy and Paste the salary table into an Excel spread sheet. compare this to collecting data from what can we do next with this kind of data...?

13 How did it go?

14 What are issues with the data? Reliability? Accuracy?

15 First Data Cleaning Steps Combine data into one data set, if you haven t done this yet. Augment collected data by team and season. Clean-up data: make salaries numbers, delete superfluous rows, extract position from names, split names in first and last (why?)... other suggestions...?

16 Your Turn The goal is to first separate the players names into name and position and then the name into first and last name. Team up with your neighbor and try to work out how this can be done in Excel

17 Before we use functions we need to back up and look at cell references

18 Referencing Cells Cells in Excel are described in form of a letter followed by a number for (column, row): What happens for tables with more than 26 columns? A B C D E

19 Absolute and Relative References A relative reference has the form letters number, eg A1, Z46, AA34 An absolute reference is written in the form $letters $number, eg $A$1, $Z$46, $AA$34 Absolute and relative references can be mixed, e.g. $letters number letters $number What s the difference?

20 Absolute and Relative References We need to reference a cell in a formula, e.g. =A1 A relative reference is storing an offset from the current cell (i.e. it depends on the cell into which you are typing =A1 ) The difference between relative and absolute references becomes clear when you try copying and pasting the formula Use =A$1 =$A1 =$A$1 for absolute references

21 Text functions in Excel LEN FIND LEFT, RIGHT, MID TRIM CONCATENATE! use built-in help to get more information on each function and see examples for their use

22 Your Turn Download the file nba-espn-salaries.xls from our website Split the names of players into tree columns: First Name, Last Name, and Position Make sure that names are cleaned of all white space Format dollar amounts to integer numbers. Sort Data according to Players last names, first names and season.! Fast track: - add column with first year of season - delete rows without information

23 Your Turn Which aspects of the data can we investigate now?! Again, team up with your neighbor and discuss for 2 min. We will collect ideas afterwards.

24 Routes of Investigation

25 Excel Functionality Working with data sets Freeze Panes ALT - W - F Autofilter Ctrl-Shift-L

26 Combining Information from different tables Do the vlookup exercises in the Juice Analytics Excel help file (see website)