Research Basics

Types of Studies

Types of StudiesExperimentalCorrelationalSurveys & InterviewsFocus GroupsObservationCase StudiesLiterature ReviewAnecdotal Evidence & Testimonials

Terms to review

Sample-particular group gathered for an experiment

Reliable-consistently measuring the same thing

Valid-accurately measuring what an experiment is attempting to measure

Variable-condition

being changed in experiment

Experimental group-group exposed to variable

Control group-group that remains consistent

Placebo-inactive or fake medication given to resemble a medication

Types of Studies

Nutrient and food studies tend to be either experimental or correlational type studies.

Experimental StudiesStudies in which conditions are under the direct control of the researcher.

Their purpose is to determine relationship between variables.

Experimental StudiesSubjects are divided into groups (control, experimental, etc.).

Then the researcher manipulates the independent variables under highly controlled circumstances.

A fitness instructor wants to test the effectiveness of a supplements on students in her exercise class. To create similar groups, the students are assigned into 2 groups at random. Students in both groups are given a pill to take every day, but they do not know whether the pill is a placebo or the supplement. The instructor gives Group A the supplement and Group B receives the placebo.  The students' fitness level is compared before and after six weeks of consuming the supplement or the placebo.  No differences in performance ability were found between the two groups suggesting that the supplement was not effective.

Limitations of Experimental Studies

A major limitation is that this method can only be used when it is practical and ethical for the researcher to manipulate the variables.

Limitations of Experimental Studies

A second limitation to this method is that FOOD experimental studies are usually done in the highly controlled setting of the laboratory.

These conditions are artificial and may not reflect what really happens in the less controlled and infinitely more complex real world.

Double Blind Placebo Experiments

The best and most reliable form of study is the double blind placebo experiment.

A treatment cannot really be said to be proven effective unless it has been tested with a Double Blind Placebo.

AKA -gold standard of research

Double Blind Placebo

In this type of study neither the subjects nor the researchers know who is getting a fake treatment (placebo) and who is getting the real treatment.

Double Blind Placebo Studies

Individuals in the control group or the placebo group don't know whether they are getting the real treatment or the placebo….(they are "blind")

Furthermore, the researchers administering placebo and real treatment also don’t know which group is receiving which treatment

Making it a "double-blind"

Double Blind Placebo

The purpose of this kind of study is to eliminate the power of suggestion.

This prevents the researchers from unintentionally tipping off the study participants, or unconsciously biasing their evaluation of the results.

Double Blind Placebo Studies * A placebo must be given to control for these improvements.

* If the people in the treatment group fare significantly better than those in the placebo group, it is a strong indication that the treatment really works.

Co-relational StudiesA co-relational study is a type of

study in which two (or more) variables are measured and compared in a group of individuals without actually experimenting on them. ◦ Example: Studies have been done

through survey’s; where they have found people who have a love for nature have more satisfaction with their lives.

◦ No specific experiment has been done to find out one causes the other-they just know there is a high association.

Correlational StudiesCorrelational studies can determine whether or not two variables

“go together” — or determine the degree to which they change together, on average in the same or opposite directions.

Positive Correlation

If two variables change together

in the same direction,

for example, if a person has a lot of money-they may buy more expensive cars, we say that the variables are

positively correlated.

Negative Correlation

If two variables

change together in

the opposite direction,

such as alcohol intake and driving ability (the more alcohol one drinks, the less one is able to drive, on average, and vice versa), we say that the variables are….

negatively correlated.

Strengths of Correlation Studies

The major strength of correlational studies is that they allow us to quickly discover general relationships among variables without having to experiment.

Correlation can be used when it is impractical and/or unethical to experiment.

Much larger samples.Cheaper

Limitations of Correlational Studies

Correlation, cannot, prove causation.

It only shows that two variables are related in a systematic way.

It does not prove nor disprove that the relationship is a cause-and-effect relationship.

Retrospective Study

A retrospective study is a study that looks backwards in time.

Retrospective StudyCompares two groups of people:

those with the disease or condition under study (cases) and a very similar group of people who do not have the disease or condition (controls).

Researchers study the medical and lifestyle histories of the people in each group to learn what factors may be associated with the disease or condition.

Retrospective Study

A study in which a search is made for a relationship between one phenomenon or condition and another that occurred in the past

(e.g., the exposure to toxic agents and the rate of occurrence of cancer in the group exposed compared with a control group not exposed).

May make use of historical information (death records, etc.)

Strengths of Retrospective Studies

Retrospective studies are good for studying a disease that takes a long time to appear.

Limitations of Retrospective StudiesThe biggest problem in a retrospective

study is that some of the information that we need may be hard to get and/or based on recall (memory).◦ Memory is selective and can introduce all

sorts of biases into a study!

Using death certificates means interviewing family which could lead to inaccuracy.◦ If the patient is alive, they may have to recall

events that happened many, many years ago!

Prospective StudyA prospective study looks forward in time.

A group of subjects is selected and watched for a long period of time.

May follow groups of individuals over time who are alike in many ways but differ by a certain characteristic (like smoking or not)

Most prospective studies are longitudinal and involve cohort groups.

Remember that Longitudinal =

over timeCohort =

the same group of people

Example: Prospective Cohort Study

For example, following female nurses (cohorts) who smoke and those who do not smoke for 40 years (longitudinal) and comparing them for rates of lung cancer and stroke.

Strengths of Prospective StudiesHave less potential for bias.

Less likely to have problems with recall.

Limitations of Prospective StudiesA prospective study is slow.

Unless you are studying a rapidly fatal disease, you have to wait years or even decades to accumulate sufficient data to draw any strong conclusions.

Naturalistic ObservationIf it is a naturalistic observation, the subjects or phenomena are not directly interfered with in any way. They are observed in their natural settings. In the social sciences this usually involves observing humans or animals as they go about their activities in real life settings. Ex. Yellow light

Surveys

A type of study where data is collected via interviews or questionnaires.

Relationships among the variables are determined from the data collected.

Strengths of SurveysSurveys also make it possible to sample a large number of subjects

Helpful in collecting data on aspects of behavior that are difficult to observe directly.

Less expensive than other kinds of research.

Limits of SurveysThe major limitation of the survey method is that they rely on the self-report method of data collection.

Self report may lead to intentional deception, poor memory, or misunderstanding of the question can all contribute to inaccuracies in the data. –ex. census

InterviewsInterviews or questionnaires commonly include an assortment of forced-choice questions (e.g. True-False) or open-ended questions (e.g. short answer essay) to which subjects are asked to respond.

Focus groups/Panels

A focus group is a form of research in which a group of people are asked about their perceptions, opinions, beliefs and attitudes about a clearly defined topic.

Focus Groups/Panel DiscussionsQuestions are asked in an interactive group setting where participants are free to talk with other group members.

Composed of six to nine participants.

A group facilitator keeps the discussion on track by asking a series of open-ended questions meant to stimulate discussion.

Strengths of Focus groupsRelatively easy to undertake Results can be obtained in a short period of time (less than 2 hours)

Social interaction in the group produces freer and more complex responses

The researcher can probe for clarification and solicit greater detail.

Limitations of Focus groupsRequires highly skilled moderator

Groups are often difficult to assemble

Individual responses are not independent of one another

Because the group is hand-selected, the results may not be representative of the general population.

Case Study

An in-depth record of one person, family, group, or phenomenon. The hope is that learning gained from studying one case or two cases can be generalized to many others.

Case StudiesIn a case study, nearly every aspect of the subject’s life and history is analyzed to seek patterns and causes for behavior.

Case studies are particularly useful when researchers want to get a detailed view of an individual's life or of a particular phenomena.

Case Studies

Typical data collected might include biographical data, medical records, family history, observations, interviews, and the results of various psychological tests.

Limitations of Case StudiesMay not be representative of the general group or population.

Since they are usually just a case or two.

Case studies tend to be highly subjective

(open to researchers opinion and bias)Behavior can only be described, not explained.

Limitations of Case StudiesCase studies often rely on

descriptive information provided by different people. This leaves room for important details to be left out. Also, much of the information collected is retrospective data, recollections of past events, and is therefore subject to the problems inherent to memory.

TestimonialsTestimonials are endorsements for products or services.

They are designed to increase trust and confidence necessary to buy products.

They can cause a “placebo effect”

When people are desperate they may cling to these testimonials and information presented as “evidence”.

Anecdotal Evidence Unreliable evidence based on personal observations and experiences that have not been scientifically proven.

Anecdotal: Hearsay or word of mouth

Testimonials & Anecdotal Evidence Testimonials are often purposely used in place of clinical or scientific evidence.

and may completely ignore research or harder evidence that points to an opposite conclusion.

Problems with testimonials

People mistake the placebo effect for true improvements.

People may choose an ineffective treatment over an effective one and end up sicker (or even dead)!

Many people who offer them are profit motivated too and don’t care about their customers.

The Major problem with Anecdotal Evidence & Testimonials

Many people have made decisions that have endangered their health or well-being based solely on anecdotal evidence and/or testimonials.

Check out the scientific findings on any new product, diet, or “superfood” you are thinking about trying out.