Variable A Variable isanything that may affect (change) the out come of the experiment. In an experiment we are looking for a “Cause and Effect” “Cause and Effect” relationship. For any effect (change) we want to know what caused it. To do this we have to be able to setup and conduct good experiments. manipulated variable The manipulated variableis the single variable you are testing independent variable experimental variable

Dependent variable Control variables are all the other variables that should be kept the same. single In an experiment, we should have as many control variables as possible. So we can clearly determine a single cause and effect relationship. Responding variable What we are measuring or calculating to see if it is affected by the experimental variable.

Control Setup not all A control setup does not have the experimental variable but has all the other variables

Analysis of Data Data tables, flow charts and graphs present the information collected during an experiment. What the data shows, any trend in information, is explained in the analysis of data.

MIX Variables – MIX M I X Manipulated (experimental) or Independent Variable is the one you are changing and is first in a data table and plotted on the X-axis of the graph.

DRY Variables - DRY DR Y Dependent or Responding variable is second column in a data table, and plotted on the Y-axis of a graph.

MAKING CHARTS Hypothesis: As weight (a force) is added to a spring it will stretch. What is the independent variable? What is the dependent variable? Force Stretch Force (N)Stretch (cm) In charts the X-axis or Independent variable is listed in the first column. Stretch -v- force The Y-axis or dependent variable is the second column.

MAKING GRAPHS 1) A title is written in Y vs X independent 2) The independent variable is plotted on the horizontal xdependent (x) axis and the dependent y variable on the vertical (y) axis. 3) Label each axis with the name of the variable and the unit. General graphing rules What kind of graph do you use for your data? Depends on the data you collect

Bar Graphs not A bar graph is used when one set of data is not numerical.

Pie/Circle graphs Pie graphs are used to show parts of a whole and percent distributions.

Line Graphs A line graph is used when BOTH sets of data are numerical

Making Line Graphs 1) A title is written in Y vs X independent 2) The independent variable is plotted on the horizontal xdependent y (x) axis and the dependent variable on the vertical (y) axis. 3) Label each axis with the name of the variable and the unit. 4) Choose a scale that makes the graph fill at least 2/3 of the graph paper. The x and y scale need not be the same. 5) Number each axis clearly. 6) Plot all points as a dot. READ 7) READ instructions carefully if you are to connect “dot to dot” or draw a line/curve of “best fit”

Data Trends same way. Direct relationship means as one variable changes, the other changes in the same way.

Other Data Trends Inverse – when one goes up the other one goes down or as one goes down the other goes up.

Now its your Turn!