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### Random sampling

each element in the population has an equal chance of appearing; reduces chance of bias

### Stratified sampling

selecting an element according to certain subgroups to diminish the change of sample flucuation; can be random stratified- accomplished by randomly selecting a proportionate number of subjects from each subgroup for the sample

### Judgement sampling

someone who knows the population selects the sample; familiarity with the population, bias introduced

### Convenience sampling

group is chosen because it happens to be convenient; may represent the population; ease for evaluator

### Ungrouped

data is presented in ascending or descending order along with the frequency of each score occuring in the data set

### Normal curve

bell, gaussian, scores are equally distributed around the mean; meand, median, and mode all have the same value

### Mean

average number of scores; add all scores and divide by number of scores; most common measure of central tendency

### Median

divides the distribution into 2 equal parts; 50% of scores lie above center, 50% of scores lie below center, not affected by extreme scores

### Mode

score that occurs with greatest frequency; corresponds to the peak of the curve when plotted out

### Standard deviation

the square root of the sample variance; most commonly uesd method of dispersion, the larger the number representing the SD, the wider the distribution curve

### Validity

the degree to which a data collection instrument measures the variable it is designed to measure; does the test really measure what it claims to be measuring?

### Intraexaminer

consistent performance by the same investigator when using a data collection instrument

### Interexaminer

consistent performance by different investigators when using the same data collection instrument

### Calibration

the process of establishing a relationship between a measuring device and the units of measure; helps increase interexaminer reliability

### Correlation co-efficient

determines the strength of relationship between 2 variables; shows a possible cause and effect; between -1 & +1; the closer to either of those numbers the stronger the correlation

### Positive correlation

direct association betwen 2 variables; as value of x increases, the value of y increases; as the value of x decreases, the value of y decreases

### Negative correlation

the score on one scale predicts an opposite score on the other scale; as the value of x increases, the value of y decreases; as the value of x decreases, the value of y increases

### T-test

a statistical hypothesis test used when comparing the statistical difference between 2 mean scores

### ANOVA

analysis of variance, used when comparing the statistical difference between 3 or more mean scores

### P-value

probability value, used when testing hypothesis; standard of acceptability is p less than or equal to 0.05, 1 out of 20 occured by chance, nothing to do with the testing situation

### Primary preventive services

involves techniques and agents to forestall onset and reverse progress of disease or arrest the disease profess before treatment becomes necessary. Ex: mechanical and chemical plaque removal, fluoride, sugar discipline

### Secondary preventive services

involves routine treatment methods to terminate a disease and restore tissues to as normal as possible; intervene or prevent the progression and recurrence of disease. Ex: periodontal debridement, restorations

### Tertiary preventive services

involves measures necessary to replace lost tissue and rehabilitate patients. Ex: prosthestics, implants

### Epidemic

an unexpectedly large number of cases of disease in a particular population at a particular place and time.

### Incidence

the number of new cases in a population at risk during a particular period of time; conveys information about the risk of contracting the disease

### Prevalence

the number of new and old cases of a disease in a population in a given period of time; tells how widespread the disease is, prevalence=past

### Retrospective studies (case control)

seek to compare thoes diagnosed with a disease with those who do not have the disease for proper exposure to specific risk factors

### Prospective studies

a cohort is classified by exposure to one or more specific risk factors and observed into the future to determine the rate at which disease develops

### Experimental studies

a study carried out under controlled situations, control group, experimental group, may be blind or double blind

### Blindness

the practice in which the researcher remains uninformed and unaware of the identifiers of treatment and control group members through the period of experiment to prevent bias

### Characteristics of an Ideal Index

simple, valid, reliable, clear, sensitive, quantifiable, objective, accepted

### DMFT/DMFS

decayed, missing, filled teeth/surfaces, irreversible, past and present caries experience w/ permanent dentition

### deft

decayed, need for extraction, filled teeth, irreversible, observable caries experience in primary teeth

### GI

gingival index, reversible, based on severity of inflammation and location, used to determine prevalence and severity of gingivitis in cohort groups

### PDI

periodontal disease index, ramjford, irreverible, prevalence and severity of periodontal disease, measures both reversible (gingitivits) and irreversible (periodontitis)

### PSR

periodontal screening and recording, assesses state of periodontal health rapid and effective, premilinary screening to determine need for full mouth periodontal assessment, uses special probe

### CPITN

community periodontal indec of treatment needs, established by WHO to determine periodontal tx needs rather than periodontal status, requires special probe

### OHI-S

simplified oral hygiene index, reversible, measures oral hygiene status, involves both debris and calculus index

### PLI

plaque index, reversible, measures difference in thickness of soft deposits at gingival margin, used in conjunction with GI

### PHP

patient hygiene performance, reversible, assess individual's performance in removing debris after toothbrushing instructions

### VMI

volpe-manhold index, reversible, used to test agents for plaque control and calculus inhibition, scores supragingival calculus following prophylaxis

### Needs assessment

process by which the program planner identifies and measures gaps between what is and what ought to be, analyze and understand the target population, to collect baseline data for program evaluation

### How to conduct a needs assessment?

direct observation, interview, questionnaire, survey, epidemilogical surveys, records, documents, charts

### Type I examination

complete examination, includes mouth mirror and explorer, lighting, radiographs, study models, tests as needed

### Objective

specific statement that describes, in a measurable manner, the desired result of the program, based on needs of target population; can be considered steps to achieve the program goals