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Lecture 4

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Simon Fraser University
Health Sciences
HSCI 307
Denise Z.

HSCI 307 Lecture #4 Tuesday, Feb. 1 , 2011 Study Designs: The Time Dimension N Cross-sectional -one point in time, less robust, is a snapshot of the current ore previous state of knowledge; L[šZZ}Á‰Œ}oKZZÀo}‰}ÀŒš]K~}ŒšZZ‰šZ]ZZZ} µŒŒ: N Longitudinal - over time, different populations at different times (e.g. every 5 years in populations with alcohol and drug consumption), time series, panel -cohort: Similar to a panel study, but observing over time a category of people who share a similar experience at one time period, e.g. Birth cohorts; allows you to asses change at a population and/or an individual level, good for both clinical practices and those that cover a broad range (e.g. homeless individuals with mental problems over 5 years-some getting housing, some using drugs, some having physical health problems, etc. to see how these factors influence mental health and how individual health status changes over time). -If following a child into adulthood, the adult will have to re-consent once they become a legal adult. N Case study -over time; Draws on the logic of analytic rather than enumerative iLµ š]}L8KLZšZššZÇ[Œ K}ŒZ Œ]‰š]À}L]L]À]µoš}‰Œ}À]ZLZ}ÁZš[Z2}]L2}L~ÁZš]ZšZŒoš]}LZZ]‰ and how do we understand it). -Considers specific context of the case in detail rather than looking for patterns in a large number of cases. Types of Data Collection Techniques Quantitative data N Experiments -Researcher/scientist manipulates the conditions for some participants but not for others and compares group responses to assess whether the condition made a difference; refers primarily to a randomized controlled experiment; populations are as similar as possible except for the one factor you wish to control in the study, e.g. drug trials (you either get the drug or the placebo, or old drug vs. new drug). N Surveys -Researchers systematically ask a large number of people the same questions. -Answers are recorded and analyzed with statistical methods. Frequently used in descriptive or explanatory research to understand an issue/research problem -produces quantitative data to provide a sense of knowledge on the topic N Nonreactive Research -Compared to reactive research such as experiments or surveys where participants are aware of their participation in a study, participants in non-reactive research are not aware that HSCI 307 Lecture #4 Tuesday, Feb. 1 , 2011 information about them is being used in a study ~µš]š[ZšZ] o µZšZ]L}ŒKš]}L]ZL}š being identified to the individual). -Includes: unobtrusive research (observations, e.g. reviewing medical records), examination of statistical information/documents and secondary analysis. Content analysis -a technique for examining the content, or information and symbols, contained in written documents or other communication medium (e.g. legal documents, newspaper articles, etc.) -This is non-reactive because the creators of the content do not know whether anyone will analyze it or not. -Most often used for descriptive purposes, but can be used for exploratory or explanatory purposes. Secondary analysis of existing data -a re-examination and statistical analysis of quantitative data that has been gathered previously. Field research -The researcher directly observes and records notes on people in a natural setting for an extended period of time (e.g. years, months, etc. depending on study). -Most often conducted on a small group of people - Typically begins with a loosely formulated idea or topic then gets elaborated further throughout the course of the study - Proceeds with researcher selecting a group or site to study -Researcher gains access (permission) then adopts a role within the group and begins observing for a period of several months to several years (e.g. boss at a manufacturing firm, elders in a tribal community, etc.) to reduce tensions among groups. -Data includes detailed notes on a daily basis (field notes) that speak to the observations you are most interested in as a researcher. Historical-comparative research -Researcher examines data on events and conditions in the historical past and/or across different cultures. -Researchers may focus on one historical period or several, compare one or more cultures, or mix historical periods and cultures. -Approach combines theory with data collection -Usually draws on a mix of evidence Quantitative Design Issues Language of variables Types of variables N Independent variable (IV): The cause variable, or the one that identifies forces or conditions that act on something else. HSCI 307 Lecture #4 Tuesday, Feb. 1 , 2011 N @Z^Ɖ}ZµŒ_ÀŒ]o N Dependent variable (DV): The variable that is the effect or is the result or outcome of another variable (the independent variable). N Intervening variable: A variable logically or temporally after the independent variable and before the dependent variable, and through which their causal relationship operates Causal theory and hypotheses N Causal hypothesis- A statement of a causal explanation or proposition that has at least one independent and one dependent variable and has yet to be empirically tested. -Can be stated in several ways: X causes Y X leads to Y X is related to Y X influences Y O]ZZZ} ]šÁ]šZz; See Box 6.7 Characteristics of Causal Hypotheses -At least 2 variables -Expresses a cause-effect relationship -Can be expressed as a prediction - Logical link between a research question and theory -Falsifiable: capable of being tested against empirical evidence -À}]µZ]L2šZšŒK^‰Œ}À_ -Not the language of science -^^šµ]Z‰Œ}ÀšZšZ‰]Œ]L µŒZZ ZZ_ -^9Œ}À_]K‰o]Z]Lo]šÇ7Z}oµš Œš]LšÇ -Too strong a term -Evidence supports or confirms the hypothesis -Evidence does not prove the hypothesis Testing and Refining Hypotheses ¾ See diagram HSCI 307 Lecture #4 Tuesday, Feb. 1 , 2011 Types of hypotheses N Null hypothesis -a hypothesis that states there is NO significant effect of an independent variable on a dependent variable -Based on the logic of the disconfirming hypotheses -ZZ} ]šÁ]šZŒo9}‰‰Œ[Z]}oZ]] š]}L -A hypothesis is never proved, but it can be disproved - A researcher with supporting evidence can say only that the hypothesis remains a possibility or
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