NUR 200 (Statistical Reasoning): Study Sample, Range, and Standard Deviation

Measures of dispersion

Descriptive statistical techniques conducted to identify the individual differences of scores in a sample

Two examples of measures of dispesion

How scores in a sample are dispersed or spread around the mean, How/the extent to which different scores (individual scores) deviate from one another

Homogeneous

Occurs when the scores are similar

Heterogeneous

Occurs when there is a wide variation within the scores resulting in an increase of values for the measures of dispersion

What is the simplest measure of dispersion

Range

Range

Includes the lowest and highest scores obtained for a variable

Calculation for ranfe

(Highest score) - (Lowest score)

What is the most common measure of dispersion

Standard deviation

Standard Deviation

Average number if points by which the scores of a distribution vary from the mean

Calculation for Standard deviation

Square root of the variance

High deviation from mean

SD (spread of scores) is large

Low deviation from mean

SD (spread of scores) is small

Mean is a measure of?

Central Tendency

When is mean a measure of Central Tendency

When data distribution is symmetrical and normally distributed

Standard Deviation is a measure of?

Dispersion (the average number of points by which the scores vary from the mean)

Likert-type scales are normally?

Ordinal, unless normally distributed

Sample Characteristics

Description of participants who comprise the study sample

How are Sample Characteristics often presented?

In a table and/or narrative of the article. Often presented in each of the groups in a study (ex. intervention and control groups)

Descriptive statistics

Calculates to generate sample characteristics

What does the type of statistic conducted depend on?

The level of measurement of the demographic variables in a study

Demographic variables

Age, Sex, Income Level, Race, Employment, Location, Homeownership, Level of Education

Demographic information can make?

Certain generalizations about groups

Clinical variables

Selective physical, emotional, and cognitive variables collected and analyzed to describe the specific clinical characteristics of the study sample

Level of satisfaction is usually?

Ordinal

When would level of satisfaction be interval?

When values are normally distributed

How can level of satisfaction as Interval level data be described?

Mean, Standard Deviation, Range

What kind of data is mean calculated for?

Interval and Ratio