Bellringer1) 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 pain 3 = 75% reduction1 = about 25% reduction in pain 4 = headache gone2 = 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 9th 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

Year living in poverty1985 11.41990 10.71995 10.82000 8.72005 9.92010 11.7

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?