UNLOCKING THE SECRETS HIDDEN IN YOUR DATA Data Analysis UNLOCKING THE SECRETS HIDDEN IN YOUR DATA

Why Do Data Analysis ? Avoids incorrect assumptions Does the data makes sense? Which one is better?

Why Do Data Analysis ? Are your assumptions correct? Did you collect enough data? If this is a model of a following body which is better? Be careful what's better mathematically is not always better scientifically

Ways to Analyze Data Plotting Data Statistics Ways to visually understand data Statistics Makes is easier to compare data Mean, Median, Mode Makes it clear if you have NOISY data Range, Variance, Standard Deviation

Ways to Analyze Data Derivatives (Slopes) Tell if changes in parameters affect data Parameter 2 has a greater effect than Parameter 1 Get more information from data Great Derivative Slope = 0.39 Slope = 0.16 Slope = 0.08

Plotting Data – Extracting from Netlogo Two ways 1st Way: Write code to extract the data you want – see File Output Example in the Code Examples Open file in setup procedure Create a write-to-file procedure

Plotting Data – Extracting from Netlogo 2nd way: Extract data from Netlogo graphs Have Netlogo generate graph on Interface page (example on later slide) Create a setup-plot procedure and a do-plot procedure Call the setup-plot procedure in setup procedure Call do-plot procedure in go procedure

Plotting Data – Extracting from Netlogo Run model until sufficient data obtained (PC) Right Click on Graph/(Mac) Select Export Choose location and File name - select save Excel File is created – Next Slide Contains all the information in the plot and input parameters used. Contains excess information about the plot (color, pen down, mode, interval…) LET’S DO IT – Open Rabbits Grass Weeds

Plotting Data – Extracting from Netlogo This is what You need

Plotting Data – Different Types of Plots All plots from http://www Bar Charts – preferred snacks Pie Charts – music preference Pets purchased at pet store

Plotting Data – Different Types of Plots All plots from http://www Line Graphs – cell phone use http://www.statcan.ca Scatter Plots http://en.wikipedia.org/wiki/Scatterplot

Plotting Data – Activity in Excel LET’S DO IT Open File Car Data Insert Chart Select type of chart XY Scatter Select Data Range Highlight data to be plotted

Plotting Data – Activity in Excel Label each data series Label Graph and Axis Select where you want graph to be (on that page -worksheet –or on another worksheet in same file)

Statistics Statistics help you Summarize data Describe data Analyze data Now it is easy to summarize, describe and analyze the data…. The blue and the pink data have the AVERAGE value (mean) but the blue data is “NOISIER” (greater standard deviation). Therefore… Hard to describe the difference Between the two data sets

Statistics – How to Calculate in Excel +,-,*,/ used for addition, subtraction, multiplication and division. Each cell has a label based on the column and row. Use cells to perform calculations instead of numbers. Example : =(A4+B4)/C4 Perform calculations on an entire column - copy and paste the equation .Warning : this changes the cell number for each line. Fix a specific cell - use the $ symbol, example (A4+B4)/$C$1 Excel has many built in statistical functions Makes life easy! E1

Statistics – Measurements of Central Tendency Mean (Average), Median, and Mode Definitions Mean (Average) – Sum divided by the number of data points Median – Middle data point when arranged from highest to lowest Mode – Most frequent value Use data set to calculate Mean (Average) Median, Mode, Max and Min Select Cell where you want the value of the function to appear Select Insert then Function Select Statistical Select function wanted (AVERAGE, MEDIAN, or MODE) then hit OK Select Range of data you want to analyze by clicking on range symbol and highlighting range. Hit enter or OK LET’S DO IT : StarlogoTNG : Fish and Plankton Netlogo : Rabbits and Grass

Statistics – Measurements of Data Spread Range, Variance and Standard Deviation Definitions Range = maximum - minimum Variance = measures noise of the data around the mean value. Standard Deviation (S) is the square root of the variance. Most commonly used measure of spread (same units as the data). Another reason to use S: ~68% of the data are in the interval Mean – S to Mean + S ~95% of the data are in the interval Mean – 2 S to Mean + 2 S ~99% of the data are in the interval Mean – 3 S to Mean + 3 S EXCEL does it for you!!! LET’S DO IT : StarlogoTNG : Fish and Plankton Netlogo : Rabbits and Grass

Derivatives What are Derivatives? Why use Derivatives? A simple calculation using data Instantaneous rate of change = SLOPE Why use Derivatives? Get more information from data More Ways to comparison data Car moving down a road Data = the distance traveled Velocity = the 1st derivative of distance Acceleration = 2nd derivative of distance = the 1st derivative of velocity Slope of distance Slope of velocity

How to Calculate a Derivative Mathematically: x = position t = time In Excel You Don’t Have To Use This Use this in Excel LET’S DO IT : StarlogoTNG : Fish and Plankton Netlogo : Rabbits and Grass