midterm Flashcards
What is biostatistics?
The use of statistical methods to analyze and interpret biological, medical, or health-related data.
What is the difference between a population and a sample in health research?
A population is the entire group of interest; a sample is a subset used for analysis.
What is the role of sampling in biostatistics?
Sampling allows researchers to draw conclusions about a population without studying everyone.
What are the two main types of data?
Quantitative (numerical) and qualitative (categorical).
What are the four levels of measurement?
Nominal, ordinal, interval, and ratio.
What is the purpose of an experiment in health studies?
To apply a treatment and measure its effect on outcomes.
What is a frequency distribution?
A table showing how often each value or range of values occurs.
What graph is best for visualizing the distribution of numerical data?
A histogram.
What does a boxplot show?
Minimum, Q1, median, Q3, and maximum values (five-number summary).
What is the class midpoint in a grouped frequency table?
The average of the lower and upper class limits.
What is the difference between a histogram and a bar graph?
A histogram is for numerical data; a bar graph is for categorical data.
What does a scatterplot show in biostatistics?
The relationship between two quantitative variables.
What are the four main measures of center?
Mean, median, mode, and midrange.
Which measure of center is most affected by outliers?
The mean.
What is standard deviation?
A measure of how spread out data values are from the mean.
How is the range calculated?
Range = maximum – minimum.
What does a high standard deviation indicate?
More variability in the data.
What is a z-score?
The number of standard deviations a value is from the mean.
What is considered a significantly low or high z-score?
≤ -2 (low), ≥ 2 (high).
What is the empirical rule?
In normal distributions: 68% within 1 SD, 95% within 2, 99.7% within 3.
What are quartiles?
Values that divide data into four equal parts.
What does Q2 represent?
The median (50th percentile).
What is probability?
The measure of how likely an event is to occur, between 0 and 1.
What is a sample space?
The set of all possible outcomes.
What is the addition rule for probability?
P(A or B) = P(A) + P(B) – P(A and B).
What is conditional probability?
The probability of an event occurring given that another event has occurred.
What is the complement rule?
P(not A) = 1 – P(A).
What is Bayes’ Theorem used for?
To update the probability of an event based on new evidence.
What is a normal distribution?
A bell-shaped, symmetric distribution common in biological variables.
What is the Central Limit Theorem?
For large samples, the sampling distribution of the sample mean will be approximately normal, regardless of population shape.
