Allied Health Statistics HOSA ILC - Week Four

Mean

The arithmetic average of a set of values; calculated by adding all observations and dividing by the number of observations.

Arithmetic Mean

The most commonly used measure of central tendency; represents the balance point of a distribution.

Weighted Mean

A mean that assigns different levels of importance to values based on assigned weights.

Median

The middle value in an ordered data set; divides the distribution into two equal halves.

Mode

The value that occurs most frequently in a distribution.

Measure of Central Tendency

A statistic that identifies the center or typical value of a data set.

Distribution

The pattern of frequencies of values in a data set.

Normal Distribution

A symmetrical bell-shaped distribution in which mean, median, and mode are equal.

Bell-Shaped Curve

The graphical appearance of a normal distribution.

Symmetrical Distribution

A distribution with equal shape on both sides of the center.

Positive Skew

A distribution with a longer tail extending to the right.

Negative Skew

A distribution with a longer tail extending to the left.

Skewed Distribution

A distribution that is not symmetrical.

Outlier

An observation that is much larger or smaller than the other values in a data set.

Effect of Outliers on Mean

Outliers significantly influence the mean.

Effect of Outliers on Median

Outliers have little effect on the median.

Range

The difference between the highest and lowest values in a data set.

Measure of Dispersion

A statistic that describes the spread of values in a distribution.

Variability

The extent to which values differ from one another.

Variance

The average squared deviation of observations from the mean.

Standard Deviation

The square root of the variance; measures average distance from the mean.

Coefficient of Variation

A measure of relative variability expressed as a percentage.

Relative Variability

Variability measured relative to the mean.

Absolute Variability

Variability measured without considering the mean.

Homogeneous Data

Data with relatively little variation.

Heterogeneous Data

Data with substantial variation.

Empirical Rule

The rule stating that approximately 68%, 95%, and 99.7% of observations fall within one, two, and three standard deviations of the mean in a normal distribution.

68-95-99.7 Rule

Another name for the Empirical Rule.

One Standard Deviation

Approximately 68% of observations in a normal distribution.

Two Standard Deviations

Approximately 95% of observations in a normal distribution.

Three Standard Deviations

Approximately 99.7% of observations in a normal distribution.

Frequency Distribution

A table showing values and the number of times they occur.

Frequency

The number of times a value appears in a data set.

Relative Frequency

The proportion of observations in a category relative to the total number of observations.

Frequency Percentage

Relative frequency multiplied by 100.

Ungrouped Frequency Distribution

A frequency distribution listing each value separately.

Grouped Frequency Distribution

A frequency distribution that organizes values into intervals or classes.

Class Interval

A range of values grouped together in a frequency distribution.

Class Width

The numerical size of a class interval.

Class Limits

The smallest and largest values that can belong to a class.

Lower Class Limit

The smallest value that may be included in a class.

Upper Class Limit

The largest value that may be included in a class.

Class Boundaries

The actual limits separating adjacent classes.

Lower Class Boundary

The lowest true value included in a class.

Upper Class Boundary

The highest true value included in a class.

Class Midpoint

The value halfway between the upper and lower class limits.

Midpoint Formula

(Lower Class Limit + Upper Class Limit) ÷ 2.

Grouped Data

Data organized into classes or intervals.

Ungrouped Data

Data listed as individual observations.

Cumulative Frequency

The running total of frequencies from the first class through a given class.

Cumulative Percentage

The running total of percentages through a given class.

Percentile

A value below which a specified percentage of observations fall.

Percentile Rank

The percentage of observations below a particular value.

Quartile

One of three values that divide a distribution into four equal parts.

First Quartile (Q1)

The 25th percentile.

Second Quartile (Q2)

The 50th percentile; the median.

Third Quartile (Q3)

The 75th percentile.

Interquartile Range (IQR)

The difference between Q3 and Q1.

Decile

A value that divides a distribution into ten equal parts.

Centile

Another term for percentile.

Histogram

A graph using adjacent bars to display the frequencies of continuous data.

Bar Graph

A graph using separated bars to display categorical data.

Pie Chart

A circular graph divided into sectors representing proportions of a whole.

Line Graph

A graph that displays trends or changes over time using connected points.

Frequency Polygon

A graph formed by connecting class midpoint frequencies with straight lines.

Ogive

A cumulative frequency graph.

Scatter Plot

A graph displaying paired observations to assess relationships between variables.

Stem-and-Leaf Plot

A display that preserves original data values while showing distribution shape.

Pictograph

A graph using pictures or symbols to represent data.

Data Visualization

The presentation of data in graphical form.

Graphical Presentation

The display of data through charts and graphs.

Independent Variable

The variable that is manipulated or controlled by the researcher.

Dependent Variable

The variable measured to determine the effect of the independent variable.

Research

A systematic investigation conducted to generate knowledge.

Research Design

The overall plan used to collect and analyze data.

Population

The complete group of individuals or objects being studied.

Target Population

The entire group to which study findings are intended to apply.

Sample

A subset of the population selected for study.

Sampling

The process of selecting individuals from a population.

Random Sampling

A sampling method in which each member of the population has an equal chance of selection.

Simple Random Sample

A sample selected entirely by chance.

Systematic Sampling

A sampling method selecting every nth individual from a list.

Stratified Sampling

A sampling method that divides the population into subgroups and samples from each subgroup.

Cluster Sampling

A sampling method selecting entire groups or clusters from a population.

Convenience Sampling

A sampling method based on ease of access.

Probability Sampling

Sampling methods in which selection probabilities are known.

Nonprobability Sampling

Sampling methods in which selection probabilities are unknown.

Sampling Error

The difference between a sample estimate and the true population value.

Sampling Bias

Systematic error caused by nonrepresentative sampling.

Bias

Any systematic influence that distorts study results.

Selection Bias

Bias resulting from how participants are chosen.

Response Bias

Bias resulting from inaccurate or misleading participant responses.

Measurement Bias

Bias caused by flawed measurement procedures.

Research Hypothesis

A prediction about the relationship between variables.

Null Hypothesis

A statement that no relationship or difference exists between variables.

Alternative Hypothesis

A statement that a relationship or difference exists between variables.

Experimental Study

A study in which researchers manipulate variables and observe outcomes.

Observational Study

A study in which researchers observe subjects without intervention.

Control Group

The group not exposed to the experimental treatment.

Experimental Group

The group receiving the treatment or intervention.