Showing patterns & trends Graphing Your Data Showing patterns & trends A picture is worth a thousand words! 2008-2009

Types of data (information) Variables what you measure in an experiment dependent variable What is measured unpredictable change: we don’t know how it will change until we do the experiment Y-axis independent variable What is changed variable predictable change: it only changes because we chose how it would change X-axis The effect of _____________ on _____________ INDEPENDENT DEPENDENT 2005-2006

Examples of experiments 1 How does fertilizer affect the growth rate of plants? we set up an experiment testing different amounts of fertilizer on different plants & measuring the growth (height) of the plants: dependent variable (Y-axis)? height of plants independent variable (X-axis)? amount of fertilizer The effect of _____________ on _____________ Amount of Fertilizer Height of Plants 2005-2006

Examples of experiments 2 How does exercise affect heart rate of 10th grade student? we set up an experiment testing different lengths of time of exercise (minutes) on the heart rate of students: dependent variable (Y-axis)? heart rate independent variable (X-axis)? minutes of exercise The effect of _____________ on _____________ Exercise Heart Rate 2005-2006

Examples of experiments 3 What’s the favorite drink of students? we set up an experiment surveying students and asking which is their favorite drink : dependent variable (Y-axis)? number of students independent variable (X-axis)? type of drink The effect of _____________ on _____________ Type of Drink How many students chose it 2005-2006

The Dependent Variable is dependent on the Independent Variable The Dependent Variable is dependent on the Independent Variable! Which is which? Growth of Plant Amount of Light 2005-2006

Making pictures out of data Graphs line graphs graphing data that shows continuous change bar graphs (or histograms) graphing data that is in disconnected groups The bars touch for a histogram and are separated for a bar graph How’s a critter to choose? 2005-2006

elevation (feet above sea level) How does elevation affect temperature? Line graph! elevation (feet above sea level) temp. (°C) 30 500 25 1000 20 1500 15 2000 10 2500 5 30 25 20 18 temperature 15 10 1200 ft? 5 500 1000 1200 1500 2000 2500 2005-2006 elevation

Which drink do you like best? number Coke 1 Pepsi Water 4 Iced tea Gatorade 3 6 Bar graph! 5 4 number of students 3 2 Red Bull? 1 Coke RB Pepsi RB water tea Gatorade 2005-2006 type of drink

We took a tally of how many students like each kind of pop… Make a bar graph to show the results Pepsi 15 Coca Cola 12 7-Up 4 Mountain Dew 8 Root Beer 2 Cherry Coke 7 Dr. Pepper 5 2005-2006

This table shows how student attendence effects their grades… Make a line graph of the data Number of Days Missed during year Regents Exam Grade 5 88 10 80 14 74 22 68 36 55 50 52 78 34 2005-2006

Questions: (write this on your graph paper) What is the independent variable? Number of days absent What is the dependent variable? grade What is the relationship between number of days missed and grade? As the number of days absent increases, Exam grade decreases!