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Descriptive statistics are used to __________ and __________ data in research studies.
summarize and describe
Inferential statistics make __________ or __________ about a population based on a sample.
conclusions or generalizations
Two types of variables in statistics are __________ and __________ variables.
discrete and continuous
Nominal data can be classified into groups in an __________ manner with no indication of relative severity.
unordered
Ordinal data are ranked in a specific order but have no __________ level of difference between ranks.
consistent
The __________ is the midpoint of values arranged from highest to lowest.
median
A __________ test compares three or more independent groups.
Kruskal-Wallis one-way ANOVA
A __________ test is appropriate for comparing the means of two independent samples.
two-sample t-test
Statistical __________ indicates whether the observed difference between groups is likely due to chance.
significance
A confidence interval (CI) provides a range which likely includes the true __________ of a population parameter.
value
What is an equal variance test?
An equal variance test is a statistical test used to determine if two or more groups have the same variance in their data. It is often a prerequisite for certain statistical tests, like the t-test.
If you have paired or matched samples what test can be used to compair the means?
Paired test
________variables are classified in an unordered manner and with no indication of relative severity
Nominal
Ordinal
Ranked in a specific order but with no consistent level of magnitude of difference between ranks
Measures of central tendency can be used with what kind of data?
continuous variables
What are the common risks of describing data using the mean?
sensitive to outliers and tend toward the tail to misrepresent data distribution.
What is the difference between interval and ratio data?
Interval data has consistent differences between values but no true zero point, while ratio data has both consistent differences and a true zero, allowing for meaningful comparisons of magnitude.
What is another name for the 50th percentile?
Median
Which measure of central tendency is least sensitive to outliers
is the median, as it is the middle value that separates the higher half from the lower half of a data set.
Describing data using the mode is not helpful when
the data has a large rage of values and each occurs infrequently
How is the standard deviation calculated?
The standard deviation is calculated by taking the square root of the variance, which measures the average squared deviation of each data point from the mean.
If you have a normal distribution, what percent of sample values will be found within 1 SD, 2SD, and 2SD?
Approximately 68%, 95%, and 99.7% respectively.
What is the interquartile range?
The interquartile range (IQR) is a measure of statistical dispersion, calculated as the difference between the third quartile (Q3) and the first quartile (Q1), representing the range within which the central 50% of data points lie.
Symmetrical or bell-shaped frequency distribution can also be called
Gaussian (normal)
What test can be used to determine if dat is normally distributed?
Kolmogorov-Smirnov
In what kind of data will the median and mean be equal?
In a perfectly symmetrical distribution, such as a normal distribution, the median and mean will be equal.
How is the standard error of the mean calculated?
The standard error of the mean is calculated by dividing the standard deviation of the sample by the square root of the sample size (n).
What is the difference between a confidence interval and SD?
A confidence interval provides a range of values within which a population parameter is expected to lie, based on sample data, while the standard deviation measures the dispersion of data points around the mean in a dataset.
What is the advantage of looking at CIs instead of hypothesis testing
confidence intervals can give the magnitude of the difference between groups
How would you interpret a CI that includes zero
It suggests that there is no statistically significant difference between the groups being compared, as zero indicates the possibility of no effect.
If you are using CIs to evaluate odds ration and RR would a value of 0 or 1 indicate no difference in risk?
A value of 1 indicates no difference in risk when evaluating odds ratios and relative risks, as it suggests that the odds or risks are equal between the groups being compared.
What is the null hypothesis in a 2-sided t-test?
The null hypothesis states that there is no significant difference between the means of the two groups being compared in a 2-sided t-test.
What does a Two 1-sided t-test (TOST) test?
It tests whether the means of two groups are not significantly different from each other within a specified equivalence margin, allowing for the establishment of equivalence rather than difference.
-in other words the means are practically equivalent
What does a traditional 1-sided t-test look at?
It evaluates whether the mean of one group is significantly greater than or less than the mean of another group, testing for a directional difference.
What is a noninferiority study looking at?
A noninferiority study aims to determine whether a new treatment is not significantly worse than an existing treatment by a predefined margin, thus demonstrating that the new treatment is at least as effective.
-in numbers this mean 1 is no more than a certain amount lower than mean 2
What is used to determine the level of acceptable error caused by a false positive?
The significance level, often denoted as alpha (α), is used to determine the level of acceptable error caused by a false positive in hypothesis testing.
What is a p-value?
probability of obtaining a test statistic and critical value as extreme or more extreme than the observed value, assuming that the null hypothesis is true.
If you have one group with a known population mean what type of parametric text can be donet to compare this with the study sample mean?
one-sample student t-test
What type of parametric test can be used to compare the mean of two independent samples?
two-sample student t-test
What does ANOVA stand for?
Analysis of variance
When would you use a t-test vs ANOVA?
One-way ANOVA is used to compare the means of __________ groups.
What is a two-way ANOVA?
What is an advantage of using repeated-measures ANOVA?
What does ANOVA stand for?
Analysis of covariance
What is ANCOVA?
What assumptions must be met to use t-test or ANOVA?
The data must be normally distributed, have homogeneity of variances (equal variances), and the samples must be independent.
What are nonpparametric tests that can be done for independent samples?
Wilcoxon rank sum test, Mann-Whitney U test, or Wilcoxon Mann-Whitney test
Kruskal-Wallis one-way ANOVA by ranks is used to compare __________ groups of independent samples.
What kind of nonparametric tests can be used for paired samples?
Sign test, Wilcoxon signed-rank test, Friedman ANOVA by ranks
Chi-square tests can be used when comparing __________ frequencies in categorical data to assess how likely it is that an observed distribution is due to chance.
What is a Type I Error?
If a Type I Error is 0.05 then what percent of the time will a type I error occur?
5%
What does the p-value tell you?
When can the null hypothesis be rejected?
When p is les than alpha
What is a Type II Error?
Statistical power is the probability that a test will correctly reject a false null hypothesis, often represented as ______________.
What does power tell you?
The ability to detect differences between groups if one actually exists
What is the difference between correlation and regression?
Correlation measures the strength and direction of a relationship between two variables, while regression is used to predict the value of one variable based on the value of another and can establish causality.
What is Pearson correlation?
Pearson correlation is a statistical measure that evaluates the strength and direction of the linear relationship between two continuous variables.
What is Spearman Rank Correlation?
Spearman Rank Correlation is a non-parametric measure that assesses the strength and direction of the association between two ranked variables.
What is regression analysis?
Regression analysis is a statistical method used to determine the relationships between variables, allowing prediction of one variable based on another.
What assumptions are necessary to use regression analysis?
What does coefficient of determination, r² =0.31 mean?
31 % of the variability in Y is explained by the variability in X
What does P<0.05 indicate?
The results are statistically significant
What is the Kaplan-Meier method?
The Kaplan-Meier method is a statistical approach used to estimate the survival function from lifetime data, commonly used in medical research to analyze time-to-event data.
What test compares the survival distribution between two or more groups?
Log-rank tesk
What assumptions must be made to use log-rank test?
Random sampling and subjects chosen independently
Consistent criteria for entry and end point
Baseline survival rate as time progresses
Censored subjects have same average survival time as uncensored subjects
What model is most the most popular method to evaluate the impact of covariates
Cox proportional hazards model
