Data Management & Graphing GRAPHING BASICS Data Management & Graphing

Data Management When performing an experiment, you will always collect data REVIEW Quantitative data – Data gathered in the form of numerical measurements Qualitative data – Data gathered by making observations using your senses Regardless of the type of data that you collect, it should be properly organized in a data table.

Data Table Format INDEPENDENT VARIABLE Label (unit) DEPENDENT VARIABLE The proper format for a data table is: Label your independent variable and unit in the first/left-most column Label your dependent variable and unit in the next/right column REVIEW: Independent Variable The thing that is changed by the experimenter (known before the experiment starts) Dependent Variable The thing that is measured in the experiment (data gathered) INDEPENDENT VARIABLE Label (unit) DEPENDENT VARIABLE Label (unit) Data

Why Graph? Graphs are an effective way to visually display the information or data collected in an experiment. Graphs can clearly illustrate a trend in information or data collected. This is one way that data can be analyzed. The shape of the trend will often have a math formula and relationship associated with it. This can help you predict data if you don’t want to gather it with an experiment

Line Graph Most often used to show changes over time or rates of change in something. It is used when you can make a sequential scale with the data being collected. Example: Change in average speed compared to the distance traveled.

Titleing a Graph A title for a graph should describe what the experiment was comparing For line graphs: Titles should list the dependent variable vs. the independent variable Temperature vs. Time All titles are placed at the TOP of the graph

Creating Line & Bar Graphs Line graphs must: use graph paper if not constructed on a computer use even graduations or scale with even increasing or decreasing increments along the axis - to determine scale for x and y axis, divide range of data by the number of lines on the axis. (data range is highest value – lowest value)

Water Temperature (°C) Calculating the Scale For example: The left hand column is the independent variable. The data range should subtract the high data point from the low data point. Data range: 17-5=12 Then count the number of lines on the axis you will be putting the scale on. For example: 22 Speed (m/s) Water Temperature (°C) 17 25 14 28 11 31 8 34 5 37 Then divide the range by the number of lines 12 = 0.54 = 1.0 22 You need to round that number up to one that is easy to count by like 0.1, 0.2, 0.5, 1.0, 2.0, 5.0, 10.0

Dependent Variable vs. Independent Variable Bar & Line Graphs line graphs are constructed on a set of axes X axis runs horizontal ( →) Y axis runs vertical (↑) These axes must be labeled properly The x-axis should be labeled with the independent variable and unit The y-axis should be labeled with the dependent variable and unit Dependent Variable vs. Independent Variable Y-axis DEPENDENT VARIABLE Label (unit) X-axis INDEPENDENT VARIABLE Label (unit)

Line Graph Rules Line graphs must: Have the origin placed to maximize the size of the graph on the space provided. Start close to your lowest number. all quadrants of the graph do not need to be included if all numbers are positive use a smooth line or curve to connect the data points NEVER CONNECT THE DOTS your teacher will tell if you should use a smooth curve or a straight line

Practice Scenario For the following scenario, pull out the parts indicated: Laura was watching a special on HGTV (Home and Garden TV) that was on the effects of different amounts of fertilizer on plant growth. It said that the more fertilizer that could be added, the more the plants would grow. She decided to experiment to see if it was true. She went to her garden and removed 6 tulip bulbs. She placed them in 6 identical pots, watered them with the same amount of water. She decided to add the following amounts of fertilizer to the plants: Plant A (0g); Plant B (3g); Plant C (6g); Plant D (9g). She went back after 10 days and measured the height of each plant. She measured the plants as follows: Plant A (5cm), Plant B (7cm), Plant C (9cm), Plant D (11cm). What is the hypothesis? What is the Control? What are the Constants? What is the Independent Variable? What is the Dependent Variable? If I add more fertilizer, then the plants will grow more. Plant A Pots, tulips, water, measured after same amt. of time Amount of fertilizer Plant growth

Practice Scenario (continued) Now, using your answers from the previous slide, correctly fill in the data table below. Consult the scenario to find the proper numbers to put in the table as well. A B C D Independent Variable Amount of Fertilizer (grams) Dependent Variable Plant growth (cm) 5 3 7 6 9 9 11

Practice Scenario (continued) Now, using your answers from the earlier scenario, correctly title and label the axes below: Plant Growth vs. Amount of Fertilizer A B C D Amount of Fertilizer (grams) Plant growth (cm) 3 6 9 5 7 11   Plant Growth (cm) Amount of Fertilizer (grams)