Dental Public Health: Research Methods for the Dental

Hygiene StudentA Slide Series Review

Why Research?

• Science which can make diagnosis, treatment, and prognosis better

• Practice utilized evidence-based theories

• Industry

• Safety

• Others

What is Research?

• Stats• Rats• Mazes

Research in Dental Hygiene

Why We Need To Be Educated in Research Methods

The Debate

• Is dental hygiene a field of study or a discipline?

Research in Dental Hygiene

• The greatest value of research is in its contribution to the body of knowledge that can be used by the practitioner.

Research in Dental Hygiene

• Why practicing dental hygienists should get involved

BS and MS Degrees in Dental Hygiene

• Where do they fit in?• Why do they help the

entire profession?

Michaels

• Research and scholarship are not merely activities; they are a way of life and a way of thinking about life. Research and scholarship are founded on skepticism, distrust of authority, constructive criticism, clarity of thinking, trust in evidence, and recognition that knowledge is tentative, conditional, and probabilistic. Research and scholarship require a way of thinking about the world and things in it that provokes the drive to search for the truth and the drive to share publicly not only the truth but the methods for searching for it. The drive to search for the truth, the drive to share the truth, and the methods of the search are relentless, uncompromising, and discomforting.

Critiquing Studies and Products

The Art of Criticism

The Art of Criticism

• Location of Published Material

• Author• Purpose of the

Publication• Statement of the

Problem• Hypothesis

The Art of Criticism

• Purpose: Should explain what is studied

• Problem: Clearly identified goal

• Literature Review: Thorough and current

• Methods: Described methods utilized, research designs, and materials to be used in the study

• Results/Discussion: Conclusions justifiable with recommendations for future studies

The Art of Criticism

• Assumptions• Limitations• Definitions of Terms• Sample Size and

Technique• Research Design• Methods and Materials

The Art of Critism

• Peer-reviewed journal• Blind review process• Referred journals

Reviewing the Literature

• What makes a great article?

• Literature Search• Reference Books• Government

Documents• Periodicals

Literature Review

• Computer Searches• Locating Articles and

Books• Organizing the

Material• Length• Stumbling Blocks

Biostatistics

Descriptive and Inferential

Measures of Central Tendency

• Mean: The arithmetic average

• Median: The middle item of the data set (midpoint)

• Model: Most frequently occurring number in the data set

Measures of Dispersion

• Range: The highest score minus the lowest score

• Variance: The sum of the squared deviation of the sample mean divided by one less than the total number of items

• Squared Deviation: The square root of the variance

Inferential Statistics

• Parametric

• Pearson Product Movement

• Spearhman Rho Product Movement

• ANOVA

• Nonparametric

• Chi Square

• Others

Depiction of Data

• Frequency Tables• Bar Charts• Histogram• Frequency Polygon• Scattergram• Pie Chart

Distribution

• Normal Distribution: a frequency distribution of scores that when graphed yields a bell-shaped curve.– Gaussian Distribution

• Skew: extreme scores that affect the distribution

Correlation

• Positive linear relationship: The scores vary together.

• Negative linear relationship: The scores are inverse.

• Perfect or strong correlation would be close to +1 or –1.

• No Correlation: Close to O

P-Values/Statistical Significance

• Significant p-values indicate that the association between the dependent and independent variables was not due to random change. Rare chance occurrences and statistically significant results <.05.

Errors

• Type I Error: Null hypothesis is false when it is actually true.

• Type II Error: Null hypothesis is true when it is actually false.

Sampling Techniques

• Random: Selected independently with an equal chance at selection.

• Systematic: Every nth subject

• Convenience: Selection from readily available subjects

• Stratified Sampling: Delineating subjects into age, weight, race, etc.

Terms to Review

• Mortality: Deaths from a given disease/condition• Morbidity: Illness from a given disease/condition• Prevalence: All existing cases of disease/condition• Incidence: New cases of a disease/condition• Epidemic: A disease/condition among many

individuals at the same time• Pandemic: Widespread outbreak of a disease/condition

across a region or continent• Endemic: Low but constant level of a

disease/condition among a population

Terms to Review

• Risk Factors: Characteristics that may increase the likelihood of disease/condition/health

• Surveillance: Methods of systems used to monitor health and disease in a population

• Etiology: The study of disease• Independent Variable: Condition being

manipulated or controlled• Dependent Variable: Measure thought to change• Extraneous Variable: Uncontrolled variables that

may affect study

Terms to Review

• Statistically Significant: Obtained result is likely to be a result of the independent variable.

• Validity: The degree to which the study measures what it intended

• Reliability: The study could be reproduced and yield the same results.

• Pilot Study: A small study done prior to a large study to help set controls

• Placebo: A nontreatment given as an independent variable, “the sugar pill”

Terms to Review

• Blind: Subject does not know whether he/she is receiving treatment.

• Double blind: The researcher and subject do not know whether subject is receiving treatment.

• Cross-over: Subject is tested on two different treatments at different times.

• Wash-out: Subject has a period of no treatment during the crossover.

• Split-mouth: Half of the mouth is used for treatment, the other half as a control.

Terms to Review

• Longitudinal Study: An investigation over a long period of time

• Prospective Study (Experimental): Clinical trials• Retrospective Study (Ex Post Facto): Looks at

population with disease/health in the past• Epidemiological Study: Study of the factors causing

disease/conditions/health• Descriptive Study: Involves description, analysis, and

interpretation of current conditions• Case Study: Intensive investigation of a person, family,

or small group in a natural setting.

Summary

• Understanding the concepts of research is necessary for the practicing dental hygienists.