Bellringer 1)What percent of subjects still had the same headache pain after taking Drug A? 2)What was the difference in percent cured completely of their headache from Drug A to Drug B? 3) Which drug is more effective in eliminating headache pain? Explain your answer. Toxico Drug Company has been testing two drugs for headache pain relief. Subjects reported results using the following categories: 0 = no change in headache pain3 = 75% reduction 1 = about 25% reduction in pain4 = headache gone 2 = 50% reduction in pain

Variables

Definition of variable Variable comes from vary or change Something that changes in an experiment.

Independent variable The variable that we manipulate or change The cause we are investigating (as opposed to the effect) Graphed on the x-axis

Dependent variable The variable that we measure or observe The effect produced by the cause Graphed on the y-axis

Controlled variable(s) (or control) Variables you make sure stay constant throughout the experiment. Often many factors affect the dependent variable—but you can only test one thing at a time, so it is important that only that one thing (the independent variable) changes

Example Will a rose plant grow better in 10 hours of direct sunlight a day or 4 hours of direct sunlight a day? My controlled variables will include: same kind and age of rose, same size and kind of pot, same kind of soil, same watering schedule, same fertilizer, same climate

Writing purpose questions What is the effect of (independent variable) on (dependent variable)?

Example 1 Two groups of students were tested to compare their speed working math problems. Each group was given the same problems. One group used calculators, the other group computed without calculators. Independent variable: use of calculator Dependent variable: speed of problem solving Controlled variables: same problems What else would need to be kept the same? Time of day, explanation of task, quiet environment, desks

Purpose Question What is the effect of calculator use on 9 th grade algebra students’ speed at solving math problems?

Making line graphs How are line graphs the same as bar graphs? x- and y-axis Label axes Even spacing Title Use tickmarks

What is different from bar graphs? On x-axis, graph right at the tickmark Use dots and connect Line graphs are used for continuous data

Important and tricky for all graphs Have to determine the range of data so you can put tick marks and label correctly Use a “squiggly” if you aren’t starting at 0 Sample data % families Yearliving in poverty Suppose there are 20 squares on the x-axis: how many should we skip? Suppose there are 35 spaces on the y-axis: what should we count by? How many should we skip? Should we use a squiggly?