Statistics Flashcards
(41 cards)
What is the null hypothesis?
The null hypothesis is that they are equally good
We don’t have to prove the alternative hypothesis; we must show that the null hypothesis is likely to be wrong.
What is a Type 1 error?
Incorrectly rejected a true null hypothesis (false positive)
This occurs when the study suggests an effect exists when it actually does not.
Think people are positive they are number 1 but it’s false
What is a Type 2 error?
Failure to reject a false null hypothesis (false negative)
This occurs when the study fails to identify an effect that does exist.
Think 2, poo, negative
What is a crossover design in clinical trials?
Every patient is their own control
This design only works if treatment does not make the patient permanently better, suitable for chronic diseases.
What does cluster randomization involve?
Randomization of groups rather than individuals
This allows for contamination across individuals.
What is the purpose of randomization in trials?
Prevents selection bias
Ensures that the groups being compared are similar at the start of the trial.
What is a triple blind study?
Person analyzing results also doesn’t know which are the treatment arms
This adds an additional layer of blinding beyond the participants and researchers.
What is a case-control study?
Looking back, good for rare conditions
This study design compares individuals with a condition to those without.
What type of study is a cohort study?
Prospective
It follows groups over time to see how certain exposures affect outcomes.
What is intention to treat analysis?
Mirrors real life and gives an unbiased effect
This analysis includes all randomized participants regardless of whether they completed the study.
What is the difference between parametric and non-parametric data?
Parametric uses normal distribution, non-parametric is skewed
Parametric tests typically assume data follows a specific distribution.
What statistical measure is used for normal distribution?
Mean
The mean is calculated by adding all values together and dividing by the number of values.
What statistical measure is used for skewed distribution?
Median
The median is the middle value when data is ordered.
What is the mode in statistics?
The most commonly occurring value
It identifies the value that appears most frequently in a data set.
What is standard deviation?
The average distance that each individual observation is from the mean.
A range of one standard deviation above and below the mean includes 68.2% of the values, while +- 2SD includes 95.4% of the data.
Define interquartile range.
It involves the lower quartile (25%), median (50%), and upper quartile (75%).
It is used to understand the spread of the middle 50% of data points.
What does the R value indicate?
The R value can range between +1 and -1, indicating correlation strength.
Perfect positive is +1, high positive is 0.8, low positive is 0.3, and no correlation is 0.
What is statistical inference?
Using statistics to make predictions.
It involves drawing conclusions about a population based on sample data.
Define confidence interval.
A range of values within which we are confident the true population value lies.
A wider confidence interval indicates more variability, a smaller sample, or a higher confidence level desired.
What does a P value represent?
The likelihood that the observed result is due to chance if there is no difference between two results.
A common threshold is p=0.05, indicating a 5% chance of the result being due to random variation.
Fill in the blank: A P value can be between _______.
0 and 1.
The smaller the P value, the greater the unlikeliness that the result occurred by chance.
What is the highest level in the hierarchy of evidence?
Systematic reviews and meta-analyses
This level includes comprehensive evaluations of multiple studies.
What type of study is ranked second in the hierarchy of evidence?
RCT (Randomized Controlled Trials)
RCTs are considered the gold standard for testing the efficacy of interventions.
What is a cohort study?
A study that follows a group of individuals over time to see how different exposures affect outcomes
Cohort studies can be prospective or retrospective.
