Research in Health Sciences

7/29/2019 Research in Health Sciences

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Understanding Health Sciences Research


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Why Do We Do Health Research?

Understand causes and consequences of health and disease

Be able to predict, control, and/ or intervene appropriately

Apply this understanding to improving health

Of individuals

Of communities


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Health Sciences Research

Different types of research, build upon each other

BENCH BEDSIDE COMMUNITY/POLICY

Done on lab bench

Usually with mice

Mechanisms

Deals with

people

Outpatient care

Research on

largecommunities

Behaviors

Ex: My plate


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The Scientific Method

Systematic Process of discovery

Empirical research

The systematic collection of data

Data comes from formal observation and/or measurement

Objective and transparent procedures

Free (or nearly) from personal biases and emotions

Methods clearly explained and reported

Scientists and lay public have access to data and results


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Steps of the Scientific Method:

Observe a phenomenon and ask a question

Form a hypothesis (is there a causal relationship; what do you

think will happen?)

Test hypothesis using empirical methods (research study)

Analyze data and draw conclusions (statistical analysis)

Communicate your results (informed literature publications,

lab report)

1.Observe & ask question 2. Form hypothesis 3. Test

4.Analyze data 5. draw conclusions

6.communicate results


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1. Observe

1. Observe a phenomenon and/or ask a question

2. Form a hypothesis

An assumption about the nature of an phenomenon

Specific and falsifiable prediction

Often takes one of two forms:

A statement about the relationship between 2 or more variables

Statement differences between groups


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Steps in the Scientific Method

1. Observe a phenomenon and ask a question


An assumption about the nature of a phenomenon

Specific andfalsifiableprediction


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2. Hypothesis formation

Hypothesis : An assumption about the nature of a phenomenon

A prediction about what will happen

A statement that often takes one of two forms:

relationship between two or more variables.

differences between groups.


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2. Hypothesis formation:

VariablesIdentify and define variables

Characteristic or property that can be measured or assessed

Need at least TWO variables

Chocolate & obesity


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2. Hypothesis Formation: Defining

VariablesIdentify which variable predicts or influences the other

Independentvariable-PREDICTOR

Dependentvariable-OUTCOME

If the independent variable changes, what happened to thedependent variable?

------------ leads to--------------

CHOCOLATE OBESITY

IndependentVariable

Dependentvariable


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Hypothesis formation: Whats

involved Identify predictor (independent) and outcome (dependent)

variables

Decide how you will define the variables

Quantitative/Numerical CategoricalDescriptive

- Can be measured - Characteristics, can be

Weight described

- Height Sex

- Age Race

- Test Scores Group membership


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Defining Variables

Quantitative/Numerical

Can be measured

Categorical/Descriptive

Characteristic, can bedescribed

Defining variables: Can you measure the variable? Or can you

describe it?

-Characteristics can be describe

-Sex

-Race

-Group membership

Height

Age

Weight

Test Scores


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2. Hypothesis formation

Defining and measuring variables

Operationalization- How variables are measured

In a study examining chocolate and obesity:

How to measure chocolate?

How to measure obesity?

CHOCOLATE INTAKE: self-reported

How many times a week did you eat chocolate?

Included ALL types of chocolate

Measured by BMI


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Variable Relationships Identify the relationship between the variables

Are we interested in how two variables change in response to

one another, or how they are related or correlated?

What is the relationship between eating chocolate and obesity?

How does eating chocolate daily affect percent body fat?

Are we interested in how two groups are different?

What is the difference in body fat between those who eat chocolate

and those who never eat chocolate (chocolate lovers vs chocolate

haters)


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Hypothesis Formation

Identifying the nature of the relationship between twoquantitative variables

How does the independent variable affect the dependent

variable?

If the Independent variable changes, what happens to the

dependent variable?

Independent

Variable

Dependent

variable

Prediction?

Independent

Variable

Dependent

variable


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Identifying relationships between

variables

Positive (direct) Relationship

Both variables move in the same direction

As independent variable increase (gets larger), the ddependet

variable also increase

As the independent variable decrease, so does the dependentvarialbe


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Identifying relationships between

variablesNegative (indirect) Relationship

Negative (indirect)-as independent variable DEcreases, the dependent

variable Increases


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Hypothesis formation: Variable

relationshipsExamining differences between two groups

Independent variable: Chocolate

Dependent variable:Obestiy

Independent

Variable

Dependent

variable


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Steps of the Scientific Method



Identify, define, and predict relationships between variables

3. Test hypothesis (research study)

Observing naturally occurring relationships

Observational or correlational

Manipulating variables to determine cause and effect

Experiment


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Testing the hypothesis: The

Research Study How you test your hypothesis depends on what your goal is

Do you want to identify or describe relationships?

OBSERVATIONAL

Do you want to see what happens to one variable when you

change another (cause and effect)?

EXPERIMENTAL


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The Research Study

How you test your hypothesis depends on what your goal is

WHO you test your hypothesis depends on:

What group you are interested in understanding

Where you do your recruiting

Who decides to sign up to participate

Population vs sample

Population: all possible individuals that might be included in your

study

Sample: The people from your population that chose to participate


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The Research Study: Sample

Generalizability- external validity

The ability to generalize to other group

In both observational and experimental research, sample size

and characteristics are important

Sample size (n)

How many participants in a study

Sample characteristics

Age, sex, socioeconomic status, race/ethnicity, location


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Steps in the Scientific Method



3. Test hypothesis (research study)

Observational research

Variables are NOT changed, only observed and measured

Experimental research

At least one variable is manipulated (changed)


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3. Test Hypothesis: Research

Studies Observational research

Variables not changes, only observed and measured

Experimental research Variables manipulated

Population vs. Sample

Pop- everyone

Sample- those who participate


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Observational Research

Uncover, explore, or define relationships between variables

Collect quantitative (numerical) data

Measurement of two or more variables

Statistically manipulate or analyze and evaluate data

Describe relationships or predict future outcomes


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Observational Research

Describe relationships or predict future outcomes

Chocolate consumption in negatively related to BMI

Observational research is correlational

Correlation DOES NOT equal causation


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Types of Observational

ResearchCross-sectional

Examines one or more groups at a single point in time

Measured an exposure and outcome once

Rely on interviews, measurements, and surveys


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Types of Observational

ResearchLongitudinal

Examines one or more groups over time

More than one measurement taken

What happens to the relation between weight, and/or chocolate

consumption over time?Types of longitudinal research

Prospective studies

Recruit subjects and observe them over time

Assess baseline characteristics with future characteristics or

disease Retrospective studies

Recruit subjects and compare current characteristics or diseasestates with past behaviors or exposures


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Observational Research: Strengths

Investigate naturally occurring relationships

Provide descriptive information

Suggest relationships and areas for further study

Generally have larger sample size


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Observational Research:

Weaknesses Observational studies do not provide proof of causal

and effect

We observe that thin people eat chocolate more than

obese people.. Bur is it the chocolate or something else

Do not always indicate directionality

Does eating chocolate lead to reduced weight, or does

being thin cause you to crave and eat more chocolate?


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Experimental Research

Research design that makes it possible to determine

cause and effect (causal inference)

ALWAYS prospective

Baseline must be established

Identify change

Control group and a treatment/experimental group

Control groupnothing changes

Treatment groupreceives a treatment


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Controlling for variables

Keep as many factors the same as possible between groups

Measure and examine other factors that can influence outcome

of dependent variable

Statistically control

Controls for confounding variables

confounding variables

Factors that influence the relationship between the independent and

dependent variable


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Experimental Research:

Reducing bias Sources of bias

Researcher

Participant/Subject

Reducing bias in research Favoring one outcome or prediction

Inaccurate conclusions/interpretations due to prejudice

Randomization Each individual has an equal chance of receiving the treatment

Reduces researcher bias & selection bias

Helps make each group equal at the start of a trial


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Experimental Research:

Reducing Bias Placebo: a treatment that does nothing (inactive), but

modified in a way to be indistinguishable from the real

treatment

Placebo effect

Blinding

Hiding or disguising who is getting what treatment

Researchers interacting with participants

Participates dont know if they are on the placebo or control

Statisticians dont know which group is which (or what the

hypothesis is)

Randomization

Each individual has an equal chance of receiving the treatment


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Types of Experimental Designs

Gold-standard

Randomized, double-blind, placebo-control trials

Strongest study design to assess the effect of an intervention or

treatment

Participants are randomized

No one knows what group is being treated or who is getting the

placebo (researchers or participants)

Human interventions (dietary and behavioral) likely to be

randomized-control trials

Randomized into control or treatment group


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Experimental study examining the hypothesis:

Eating chocolate will cause individuals to lose weight

Independent variable? Chocolate

Dependent variable? Obesity/BMI

Nature of relationship (positive/negative)?

Chocolate

IntakeObesity


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How could we operationalize these variables?

Give participates choc.

3 times a week

Measure weight after

12 weeks

Chocolate

Intake

Weight


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Eating chocolate will cause individuals to lose weight.

How do we set up the study to control for variables and test

cause and effect?

1. Begin with 2 groups that are approximately EQUAL at the

beginning2. Only manipulate one variable

Keep all other variables approximately the same

Calorie intake

Fat, carb, protein intake

Physical activity level

Interactions with researchers

How do we know it is chocolate and not another factor?


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think will happen?)

Test hypothesis (research study)



lab report)


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Analyze data and draw conclusions

Statistically analyze data

Determine the significance of results (p-value


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Data Analysis

Analyze data and draw conclusions

Statistically analyze data

Describe the sample

Number

Demographic characteristics Measurements

e.g. mean, range, standard deviation

Statistical tests are used to determine the nature of arelationship between 2 variables

Is it a TRUE relationship or is it due to chance P-value

What is the relationship?

Positve/negative

Difference or no difference


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Data Analysis: Statistical

Significance Statistical tests are used to determine the nature of a

relationship between 2 variables

Is it a TRUE relationship or is it due to chance?

The p-value is often used as a cut-point for statistical

significance Probability value

What is the probability that a particular value occurred by

chance, assuming there is no relationship?

P


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Statistical Significance

p-values come in all forms

0.05 is the cut off

Often see 0.01, 0.001, .0000

NOTE: A smaller p-value does not mean a result is more

significant or stronger p


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Data Analysis: T-tests and

Group DifferencesExamining differences between two groups

T-tests (and F-tests) statistical procedures to compare two (or

more) group means

Statistical difference between two group means yields a p-

value


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Data Analysis: Correlational

Coefficient and linear relationships Linear relationships

as X changes, Y also changes

Numerically quantify the relationship between the dependent

(Y-variable) and independent (x-variable)

l l l


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Data Analysis: Correlational Co-

efficient Pearson product-moment correlation (r)

Measure of the strength of a correlation between variables

Range: -1 to +1

Positive values=direct relationship

As one variable increases, related variable also increases

Negative value=indirect relationship

As one variable increases, related variable decreases



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Drawing Conclusions

Drawing conclusions

CHOCOLATE

INTAKE

Body

fatness

r= - 0.11

p-value=0.01

What can we conclude about chocolate and body weight?


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Error in Research

No research study or researcher is perfect

Measurement error

Incorrect use of measurement tools

Measurement tools that dont measure what they are meant to

measure Researcher error

Recording results

Implementing experimental procedures

Participant error Memory bias (record incorrectly)

Social desirability bias

Misunderstanding of the questions


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think will happen?)

Test hypothesis (research study)



lab report)

S f h S i ifi M h d


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Communication Communicate your results

Publish in peer-reviewed journals

Present at conferences

Write lab reports (in this class)

Communications must be transparent and clear Communicate purpose, methods, analysis & results

Allow for critique and feedback

Demonstrate reproducibility


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Peer-reviewed Scientific Literature

Peer reviewed (aka refereed)

Submit research articles to journals for publications

Expert review and critique research

Provides check on research promoting publication of only

quality, systematic, and informative research

Peer-reviewed journals

Specific subject areas

Experts on the editorial boards & as reviewers

P i d (I f d)


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Peer-reviewed (Informed)

Literature Caveat: All published research is not good research?

It is still your responsibility as a good consumer to critically

evaluate the evidence to form your own opinion

Methodological weaknesses

Design issues

Sources of bias

Analytical weaknesses

Data open to interpretation


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Using Scientific Research

One study is generally NOT enough evidence to support a

particular treatment or course of action at least not as a

standard

Compile findings from multiple studies of different types

Explain health and diseases

Identify effective treatments and interventions


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Evidence Based Practice

Applying the best available research results (evidence) when

making decisions about health care. Health care professionals

who perform evidence-based practice use research evidence

along with clinical expertise and patient preferences. Systematic

reviews (summaries of health care research results) provide

information that aids in the process of evidence-based practice.

- Agency for Healthcare Quality Researchhttp://effectivehealthcare.ahrq.gov/glossary-of-terms/?filterletter=e


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Evidence Based Practice

Relies on scientific research studies

Based on numerous and varied studies

Standards of practice are NOT based on

One study

Opinion

Value

what weve always done


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Evidence Pyramid

Weak Evidence

Strongest Evidence

Systematic Reviews

Randomized controlled trials

Cohort studies

Case-control studies

Case series

Case reports

Ideas, Editorials, Opinions

Animal research

In vitro (cell) research

Documents

Research in Health Sciences