Interpreting Graphs Why bother with graphs? Line Graphs Constructing Line Graphs Bar Graphs Pie charts Scatter plots

How to Interpret Graphs

Why are graphs useful? Graphs are a quick way to visualize trends or to make comparisons.    

Graphs provide a visual, as opposed to text.  

Looks like all those hours of science class paid off

Types of Graphs Line graphs- used to measure data over time Bar graphs- used to compare values Pie charts- used to compare values (usually percentages) Scatter plots- used to show trends and relationships among a large number of data There are typically two variables that you “map out” when graphing. -The respondent variable- what is being measured/observed -The manipulated variable- what is changed during the experiment to invoke a change in the respondent.

This is a simple line graph charting temperature This is a simple line graph charting temperature. Temperature is labeled on the "y" axis and the dates (Jan 1-7) is labeled on the "x" axis. During the first week of January, which day was the coldest? ______ What was the temperature on January7th? ______ Which day does the temperature peak? ____ January 1st ~39o F January 4th The respondent variable is the temperature, the independent variable are the dates.

Practice Constructing a Line Graph Data to graph: Year 0 - 10 frogs Year 5 - 20 frogs Year 10  - 60 frogs Year 15 - 120 frogs Year 20- 120 frogs Practice Constructing a Line Graph Number of Frogs 150 140 Time or trials are always placed on the x-axis The variable goes on the Y axis. Your numbers MUST be evenly spaced for accuracy. 130 120 110 100 90 80 70 60 50 40 30 20 10 5 10 15 20 Year

What if time isn’t a variable on your graph? Usually the X axis has the independent variable (what you can manipulate or adjust) and the Y has the responding variable (what is measured/counted/observed) Multiple carts are pushed down a track with different sized weights attached to them. The distance traveled was measured. Distance (m) 100 90 Weight        Distance 1   kg            150 m 2   kg            140 m 3   kg            120 m 4 kg              90 m 5  kg             70 m 6 kg              50 m 7 kg              30 m 80 70 60 50 40 30 20 10 1 2 3 4 5 6 7 Weight (kg)

Line graphs can have multiple lines

Practice: What if the data is not so easy to place? Temperature & Number of turtle eggs hatched (out of 20) 60 degrees = 3 eggs 62 degrees = 4 eggs 65 degrees = 7 eggs 69 degrees = 11 eggs 72 degrees = 16 eggs 75 degrees = 17 eggs Finished early, analyze the trend of the graph? T-itle I-nterval neat and spaced C-olor bars OR connect dots A-xis L-abeled S-cale makes sense

Graphs show us trends and relationships among data Graphs show us trends and relationships among data. There are generally two types of relationships that data will exhibit: inverse and direct. If one variable increases and the other decreases- they share an inverse relationship. If both variables increase or decrease together- they share a direct relationship.

Inverse Relationships- As one variable increases, the other factor decreases. Examples) As you exercise more, your risk for heart disease decreases. The farther I drive, the less distance I have to reach my destination.  

Direct relationships occur when the two variables increase or decrease together. Examples: The higher your temperature, the higher your perspiration rate is. As the diameter of a pipe increases, the flow of water through the pipe also increases.

Direct or Inverse? Refer to your practice line graphs. Frogs vs. Time- direct or inverse (circle one). Weight vs. Distance- direct or inverse (circle one)

Bar Graphs are used to compare values. What is the most common shoe length?  ___________ What is the least common shoe length? ___________ How many people have shoes that are 26 cm long? ________ 27 cm 21, 29, 30, 31 cm 2

Pie charts are also used to compare values (usually as a percentage but not always).

What can you expect to spend most of your time doing at Disneyland? What can you expect to spend least of your time doing at Disneyland?

Roughly what percent of Federal spending does national defense account for? percent does our nation spend on education? ~20% ~4%

Scatterplots are used to compare trends among many data points.

What do each of the dots represent? _______________ age What do each of the dots represent?  _______________ Approximately how old are husbands of 40 yo wives?____________ Approximately how old are wives of 70 yo hubsands?____________ MOST ages lie within which range? ________________ ~43 ~65 ~38-44

For each scenario, choose which type of graph would be best to use (line, bar, pie, or scatter plot).   1.  To show how eating vegetables over a 10 year period can lower cholesterol. _______________ 2.  To compare the leg lengths and antennae lengths of crickets. ____________________ 3.  To analyze the relationship between hours studying for a test and test scores among students. _____________ 4.  To show the percentages of students in class that are male vs. female ________________. 5.  To compare the salaries of 4 different professions: teacher, veterinarian, software engineer, banker ________ Line graph bar graph Scatter plot Pie chart bar graph

Thank you for your purchase. I’m an educator, just like you Thank you for your purchase! I’m an educator, just like you. I sincerely desire to provide products that are of high quality, because I know the importance of our shared profession. Please honor the time and effort put into this product by not giving it away to others. Please read and abide by the copyright statement. Your purchase allows you to return to your purchases page at Teachers Pay Teachers to purchase additional licenses at a reduced cost for your colleagues. © Copyright 2013 Vanessa Jason (“Biology Roots”) All rights reserved. Permission is granted to copy pages specifically designed for student or teacher use by the original purchaser or licensee. The reproduction of any other part of this product is strictly prohibited. Copying any part of this product and placing it on the Internet in any form (even a personal/classroom website) is strictly forbidden. Doing so makes it possible for an Internet search to make the document available on the Internet, free of charge, and is a violation of the Digital Millennium Copyright Act (DMCA).