Biostatistics for Dentisrty Flashcards
Qualitative data is
discrete
Sensitive to extreme values
Means
Less sensitive to extreme values
Median
Measure of how much the individual data points vary around the mean
SD
Count of a given outcome or in each category
Frequency
count of a given outcome per hundred showing the proportion of each category out of the total
percentage
As X increases, Y increase has what type of linear value
postive
As X increases, Y decrease has what type of linear value
negative
What value can lie between -1 and +1
correlation coefficient
What is the same for correlation coefficient
r
The closer (r) is to -1 or +1 means what
strong correlation
The fraction of variation in Y explained by X
square of correlation
The (lower/higher) the r squared better fit to the regression line
higher
Usually states that there is NO difference between two groups being compared
Null hypothesis
States that there is no effect of a product or intervention
Null hypothesis
Hypothesis testing that is testing if there is no difference
Non-directional
Hypothesis testing that is comparing cases and controlled
directional
In this type of hystohesis testing the mean is the key data point, not the individual
Non-directional
In non-directional hypothesis testing what is the used
mean
Rejecting the null hypothesis that is actually true about the population is what type of error
Type I error
Type II error is related to
Power
The level of statistical significance is described as
alpha
alpha is commonly set at
0.05
The maximum of incorrectly rejecting the null hypothesis when it is actually true
alpha
Probability of making a type II error
Beta
Failing to reject the null hypothesis that is actually false in the population
Type II error
The probability of a type II error is described as
beta
How is power calculated
1-beta
Is related to the sample size used in the study
Power
Is the probability, assuming that the null hypothesis is true, of seeing effect ad extreme or more extreme than by chance
P-Value
Reject the null hypothesis if the p-value is what to alpha
less than or equal to
Fail to reject the null hypothesis if the p-value is what to alpha
greater than
The range of values about the sample statistic that we are confident that the true population parameter lies
confidence intervals
Statistical test that can be used to determine whether the mean value of continuous outcome variable differs significantly between two independent groups
T-test
Test that cannot be used for nominal data
T-Test
Test that is used with numerical data
T-Test
Test that compares two means
T-Test
Assumes a approximate normal distribution of the variable of interest in the groups being compared
T-Test
Used with yes or no answers
Chi-squared test
Used with categorical data
Chi-squared test
Can be used to compare the proportion of subjects in each of two groups who have dichotomous outcome
Chi-squared test
Used when null hypothesis is “there is no difference . . .” vs. “there is a difference”
Chi-squared test
Used when comparing two or more means
ANOVA
Uses F-statistic
ANOVA
if we fail to reject the null hypothesis in ANOVA means that all groups are
Equal
Analysis of variance
ANOVA
Probability that chance is responsible of an observed difference
statistical significance
Are the findings important from a clinical standpoint?
Clinical significance
Does a P -value say anything about clinical relevance or quality of study
No
Do statistics tell us about causality
NO
Systematic error in the design, conduct or analysis of a study that results in a mistaken estimate of an exposures effect on a disease
Bias
Systematic error in selecting subjects into one or more of the study groups based on their status
selection bias
Errors in procedures for gathering relevant information
information bias
situation in wich a non-causal association between a given exposure and an outcome is observed as a result of the influence of a third variable
confounding
Can lead to conclusions a causal relationship when in fact there is none
confounding
confounding is not
all or none
