AFDA – Unit 9: Statistics and Surveys Day 3 Notes: Experimental Design Name: _________________ Block: _____ Date:_______ Today we will learn about experimental design. Experimental design involves a very meticulous procedure for ________________ the environment surrounding _______ variables. ________________ group – the group that will ________________ being studied. ________________ group – the group that receives ______ treatment. ___________________ - each group should be selected by using a random process. Ex: Assign numbers and use a random number generator ________________ – a ________________ treatment _______________________ – the power of the human mind to affect positive results without treatment. ______________________- An experimental design where the subjects or the evaluators do not know who is in which group. ________________ blind – when the person administering the ________________ or placebo knows which group gets what but the subjects do not know. ________________ blind – when both the ______________ and the ____________ do not know who is in which group. ________________ - the ability to ________________ the experiment to help verify or deny the claim. ____________ - the arranging of experimental units into groups with _____________ factors to help eliminate a lurking variable. Ex: Separating subjects into male and female before selecting a control group and a treatment group. **Experimental design seeks to establish a CAUSAL (cause/effect) relationships between two variables. Experimental design includes ____________________, _____________________, _________________________, and ______________________________________ . Examples: 1. A researcher is studying the correlation between caffeine consumption and school performance. The researcher groups students into male and female. The researcher then picks 30 random boys and 30 random girls. Students’ caffeine consumption is tracked over 9 weeks and their grades are compared. a) Is this an example of an experiment? Why or why not? b) What types of techniques are used to eliminate bias? c) What could the researcher add to the design to make this a better study? 2. A researcher is studying the correlation between eating an apple a day and doctor visits. The researcher hires another person who randomly selects participants using a random number generator. The first half is instructed to eat an apple a day and the second half is instructed to not eat any apples. The researcher tracks all participants for a period of two years to see how many doctor visits each patient makes. a) Is this an example of an experiment? Why or why not? b) What types of techniques are used to eliminate bias? c) What could the researcher add to the design to make this a better study? 3. A researcher is studying the correlation between a specific weight loss pill and the presence of obesity. The researcher randomly selects patients who suffer from obesity he then puts them in groups according to their gender. The researcher then randomly determines which patients will take the medication and which patients take a placebo pill. The researcher tracks the weight loss of each patient in each gender over a period of 9 mo. a) Is this an example of an experiment? Why or why not? b) What types of techniques are used to eliminate bias? c) What could the researcher add to the design to make this a better study?