Identify the independent variable, dependent variable, experimental and control groups in the following study. A group of college students were given a short course in speed-reading. The instructor was curious if a monetary incentive would influence performance on a reading test taken at the end of the course. Half the students were offered $5 for obtaining a certain level of performance on the test, the other half were not offered money. ________________________________________________ Objective: Determine the independent, dependent, and control variables in an experiment. Period 2 only: Turn in homework (precision v. accuracy) Period 5 only: Turn in hypothesis testing data sheet Catalyst: 9/16/10

Agenda -Catalyst (7) -Precision v. Accuracy Notes (15) -Precision v. Accuracy worksheet (10) -Scientific Method Sequencing and variables (15) Homework: Study for quiz tomorrow looking at weekly objectives

Accuracy v. Precision Accuracy – How close the measurement is to the true value Precision – How closely multiple measurements agree – How exact that measurement is

What affects accuracy and precision? Accuracy – Calibration of the measure; scale zeroed or not – How carefully measurements are made – How many measurements go into an average Precision – Size of intervals; cm v. mm – Reliability of measure; mood measured on different days

Measuring accuracy and precision Accuracy – Distance from “true” value Precision – Range of results – Standard deviation of results

Scientific Method Sequencing I will pass out envelopes with cards inside with the steps of experiments;Put the cards into the correct order (Question, Hypothesis, Experiment, Data, Conclusion) Write the letter of the card which fits each part for that experiment on your record sheet (e.g., headache holly goes in the first list) On the back, for each experiment, write the dependent variable, the independent variable and a control variable When finished, shuffle the cards and swap envelopes until you finish all 6 experiments.