Variable Relationships  Kerry Tracy 2012

Scientific Method 1. Ask a question or state a problem 2. Do background research 3. State a hypothesis 4. Test the hypothesis with an experiment 5. Analyze the data and draw conclusions 6. Report results

Variable Relationships In order to analyze your experiment data, you have to determine if the independent variable causes a change in the dependent variable or not. Variables can have a direct relationship, inverse relationship, or no relationship.

Variable Relationships Direct relationship In a direct relationship, when one variable increases, so does the other; or as one variable decreases, so does the other. If the variables move in the same direction, they have a direct relationship.

Variable Relationships Direct relationship For example, as the cash amount of a gift card increases, the amount of songs you can purchase with it on iTunes also increases. Both variables on that graph would increase, showing a direct relationship between amount of the gift card and the amount of songs you could purchase.

Variable Relationships This graph shows a direct relationship. Both variables increase together. This relationship creates an upward slope.

Variable Relationships Inverse relationship In an inverse relationship, when one variable increases, the other decreases. If the variables move in opposite directions, they have an inverse relationship.

Variable Relationships Inverse relationship For example, as the amount of time spent on homework increases, the amount of time left to play video games decreases. There is an inverse relationship between time spent on homework and video games.

Variable Relationships This graph shows an inverse relationship. One variable increases as the other decreases. This relationship creates a downward slope.

Variable Relationships No relationship Sometimes variables are not related; one variable does not cause a change in the other. In the variables have no relationship, there won’t be a continual upward or downward slope on the graph. The data points will be scattered.

Variable Relationships No relationship For example, if you graphed the amount of letters in your name vs. the number of minutes you spend on the computer each day, the graph would likely show the two are not related.

Variable Relationships This graph shows the variables have no relationship. The points are scattered. The data slope does not show an upward or downward trend.

Your Turn It’s your turn to try it out!