Lecture 32/Chapter 27 Step 2: Consider 7 Critical Components - PowerPoint PPT Presentation

Seven Guidelines (Review) Step 1: Determine if study was sample survey, experiment, obs study, census, or anecdotes. Lecture 32/Chapter 27 Step 2: Consider 7 Critical Components (details). Putting Skills to the Test Step 3: Check for “Difficulties and Disasters” (sampling p. 69, exp. p. 90, obs. studies p. 96) � Seven Guidelines Applied to Night Light Article Step 4: Is info complete? If not, find original? � Chi-Square Analysis of Night Light Data Step 5: Do results make sense? Step 6: Are alternative explanations possible? Step 7: Do results affect your attitude/lifestyle? Seven Critical Components (Review) Example: Night Lights & 7 Guidelines Source of research and funding � Background : Night Lights Bad for Kids? 1. Researchers who had contact w. participants � Question: How does each guideline apply? 2. Individuals studied, how they were selected � Response: Step 1 (design): retro obs study 3. Variables studied [measurements, questions] Step 2 (7 Components): 4. #1 source/funding: (reputable?) Setting (time, place) 5. _________________________________________________ Confounding variables [differences besides 6. #2 researchers having contact w. participants: factor of interest] if causal relationship is ______________________ claimed #3 individuals/how selected: Extent or size of claimed effects/differences 7. ________________________________________________

Example: Night Lights & 7 Guidelines Example: Night Lights & 7 Guidelines Response: Step 3 Difficulties? (Obs. p. 96) � Response: Step 2 (7 Components) � Confounding variables? continued: 1. __________________________________________ explan: ______________________________ #4 variables: _____________ Extending results inappropriately? response: ____________________________ 2. Using the past as a source of data? 3. #5 setting: ______________________________________ _________________________________________ #6 confounding variables (diffs in groups compared): ____________________ #7 magnitude/quantify effect: ____________________ Example: Night Lights & 7 Guidelines Example: Night Lights & 7 Guidelines Response: Step 3 Difficulties(sampling p.69) Response: � � Step 4 Information complete? Using the wrong sampling frame? ______ 1. Step 5 Do results make sense? ___________________________________________ ________ Not reaching individuals selected? _____________________________________ 2. Step 6 Alternative explanation? Having a low response rate? ________ 3. _______ Volunteer/self-selected sample? _____________________________________ 4. _______ Convenience or haphazard sample? 5. ______________ Step 7 Results’ impact on you?

Example: Night Lights & Chi-Square Example: Night Lights & Chi-Square � Background : Article reports % myopic: darkness � Background : We have table of observed counts. 10% of 172; nightlight 34% of 232; lamp 55% of 75 � Question: What are the expected counts? � Question: What are the observed counts? � Response: � Response: Myopic OK Total Obs M NM Total Exp M NM Total Darkness 172 D 172 D 172 Nightlight 232 N 232 N 232 Lamp 75 L 75 L 75 Total 479 T 137 342 479 T 137 342 479 Example: Night Lights & Chi-Square � Background : Observed and expected counts are Obs M NM Total Exp M NM Total D 172 D 172 N 232 N 232 L L 75 75 T 137 342 479 T 137 342 479 � Question: What is chi-square? Conclusions? � Response: _____________________________________________