Final Flashcards by Nick Murray

The extent to which a specific intervention/procedure produces a beneficial result under IDEAL conditions

Efficacy

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The extent to which a specific intervention/procedure when deployed in the field in routine circumstances works

Effectiveness

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Hierarchy of Evidence

Systematic reviews and meta-analysis
Clinical human trial
Longitudinal cohort studies
Case-control studies
Descriptive and cross-sectional studies
Case reports and case series
Personal opinion, subjective impressions, anecdotal accounts

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Impact Factor

Total number of citations to articles appearing in journal
___________
Total number of articles published

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Medical research that follows subjects to assess occurrence of disease (future occurrence). Select based on risk factor. Less bias but more time/money.

Prospective Cohort Study

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Groups are defined on the basis of exposure to a suspected _________ for disease

Risk factor

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Historical study (looks back on records). Subjects selected based on whether they have disease or not. Efficient in time/cost but susceptible to bias.

Case-Control Study

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Snapshot assessment of prevalence of disease/exposure

Cross-sectional Survey

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Describe the experience of a single individual/group with similar diagnosis

Case Reports
Case Series (multiple CR)

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An element, feature, or factor that is liable to vary or change

Variable

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A measurement scale based on categorization (gender, political party)

Nominal

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A measurement based on relationship between observations (poor-fair-good scale).

Unequal intervals.

Ordinal

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Continuous measurement scale of equal units of measurement. (Fahrenheit, Celsius)

Known distance between numbers.

Interval

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Continuous measurement scale of equal units with a true zero point at its origin. (Mass, time)

Ratio

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Most useful with nominal scale

Mode

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Most useful with ordinal scale.

Median

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Difference between max and min

Range

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A lower and upper confidence bound

Confidence Interval

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Average of the square of deviations of measurements about their mean. BEST MEASURE OF SPREAD.

Variance (s2)

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Positive square root of the variance. “Natural” variability

Standard Deviation (s or SD)

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Measures the percentage of spread

Coefficient of Variation (CV)

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SD of sample means. “Error” variability

Standard error (SE)

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Used to measure variability to individual subjects around sample mean

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Used to asses how accurately a sample mean reflects the population mean

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A mathematical statement of no difference. Theory proven when this is rejected.

Null Hypothesis

Proven by showing that the null hypothesis is unlikely to be true

Alternate Hypothesis

Directional Hypothesis

One-tailed

Non-directional hypothesis (states groups are unequaled but no direction difference specified)

Two-tailed

The variable we measure and compare (outcome variable)

Dependent variable

The variable we manipulate (grouping/predictor variable). Used to differentiate groups in a study.

Independent variable

Alpha/p-value error. Probability of rejecting null hypothesis when it is actually true

Type I error

"Beta error" Probability of accepting the null hypothesis when it is false

Type II error

The probability of rejecting a null hypothesis when it is false. The ability of the statistical test to detect a specified difference if that difference exists.

Power

Most useful with interval/ratio (continuous) measurement scales

Mean

According to the _______, the sample means of a _____ distributed population will have a ______ distribution

Central Limit Theorem Non-uniformly Uniform

A language-based statement of what we are trying to prove.

Research Hypothesis

Types of papers published in journals:

1. Research reports 2. Reviews of literature (summarization) 3. Commentaries

Components of a Research Report:

1. Title 2. Authors 3. Date of submission and acceptance 4. Abstract/summary 5. Intro 6. Materials and Methods 7. Results 8. Discussion 9. Conclusion

The mean is making an _____ from your sample to the entire _____.

Inference Population

Gives you an idea of how much variation there is in results.

Tells you that if you repeated your experiment many times, the true population mean would be within 1 SD of your sample mean 60% of the time.

As you decrease the amount of error (95 -> 99%) the confidence interval will _____

Increase

How are Alpha and Beta related to each other? How are they related to the sample size (N)?

They are inversely proportional to each other. (Alpha increases -> beta decreases) They are inversely proportional to the Sample Size (sample size increases -> alpha and beta decrease)

For nominal/ordinal the best measure of spread is:

Range

Middle 50%

Interquartile Range

Methods to increase power: 1. (Inc/Dec) The type 1 error you are willing to tolerate. 2. (Inc/Dec) sample size 3. (Inc/Dec) deviation from null hypothesis you are willing to tolerate 4. (Inc/Dec) variability 5. Use a _____ hypothesis if appropriate 6. Use the most ______/_____ statistical test

1. Increase 2. Increase 3. Increase 4. Decrease 5. Directional alternate 6. Efficient/Powerful

Statistical Decision-making steps:

1. Make a research question 2. Define variables 3. State null and alternate hypotheses 4. Choose statistical test 5. Determine type 1 error you will tolerate and sample size required 6. Conduct experiment 7. Calculate the test statistic 8. Determine type 1 error (p-value) using sampling distribution 9. Conclude

Describe patterns of disease occurrence in relation to persons, place, and time. This data essential for public health administrators and epidemiologists.

Descriptive Studies

Measures representing characteristics of entire populations are used to describe disease in relation to some factor (age, food, health services)

Correlational Studies

Measures strength of association/relationship

Pearson Coefficient (r)

Indicates change in dependent variable for every one unit change in independent variable

Regression coefficient (B1)

Probability that the results occurred by chance alone and the null hypothesis is really true

P-value | If p-value is less than .05, then reject the null

Indicates value of the dependent variable when the independent variable is 0

Intercept (B0)

Measures the strength of the relationship by "explaining" the % variance of the dependent variable "accounted for" by the independent variable

Coefficient of Determination (R^2)

Correlation Studies strengths and limitations:

Strengths: - Quick - Cheap - Uses available data/info Limitations: - Can't link disease/exposure to individual (data is non-specific) - Can't control for effect of potential confounding - Lack of correlation doesn't imply an absence of association - ONLY VALID FOR RANGE STUDIED

Test used to determine if your sample is different from a specified population

Dependent (One-sample) t-test

Divides/partitions the variance of the entire experiment into two or more components

Analysis of Variance (ANOVA)

Represents the average SS for each line

Mean Squares (MS)

Assumptions of ANOVA tables

- Interval/ratio (continuous) measurement scales - Populations follow normal distribution - Populations have equal variance - Independent groups

Theoretical basis for comparisons prior to study. Does not involve testing all possible comparisons. A priori.

Planned Comparisons

Effects suggested by data. A posteriori (post hoc)

Unplanned Comparisons

Single-Variable Tests:

Z-test and T-test

We know the population standard deviation, we estimate the mean from a sample

Z-test

We estimate both the mean and standard deviation

T-test

Dependent Variable- Nominal/Ordinal Independent Variable- Nominal Ordinal Test type?

Chi-Square

Dependent Variable- Nominal/Ordinal Independent Variable- Continuous Test types?

Logistic Regression

Dependent Variable- Continous Independent Variable- Continuous Test types?

Correlation and Regression

Likelihood of developing the disease in the exposed group relative to those not exposed

Relative Risk (RR)

Dependent Variable- Continuous Independent Variable- Nominal/Ordinal Test types?

t-Test or ANOVA

The number of people in a population who have a given disease at a given point in time. Frequency of all current cases of disease.

Prevalence

Measure of the number of lesions/period of time. Only measures the numbers of new initial lesions per unit of time.

Incidence

Describes the amount (prevalence) of dental caries in an individual.

DMFT/DMFS Decayed Missing Filled Teeth/Surfaces

Chi-square tests and Fisher's Exact tests are similar to _____ tests

Linear Regression and Correlation

Wilcoxon Rank Sum Tests are equivalent to _____ tests

Two-sample t-tests (Independent t-tests)

Kruskal-Wallis Tests are equivalent to _____ tests

ANOVA

Wilcoxon Sign Rank Tests and McNemar tests are equivalent to ______ tests

One-sample t-test (Paired t-test) (Dependent t-test)

Degrees of freedom of Dependent/One-sample t test is equal to

N - 1 | N = population size

Degrees of freedom for independent (two-sample) t-test is equal to

Total sample size minus 2

Each individual is measure multiple times

Dependent (one-sample) t-test

Each individual is measured only once and two groups are compared

Independent (two-sample) t-test

Final Flashcards

(80 cards)