Nursing Research (Lobiondo-Wood) Chpt. 16

Front 1

Analysis of covariance (ANCOVA)

Back 1

A statistic that measures differences among group means and uses a statistical technique to equate the groups under study in relation to an important variable.

Front 2

analysis of variance (ANOVA)

Back 2

A statistic that test whether group means differ from each other, rather than testing each pair of means separately. ANOVA considers the variation among all groups.

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categorical variable

Back 3

A variable that has mutually exclusive categories but has more than two values.

Front 4

chi-square (x2)

Back 4

A nonparametric statistic that is used to determine whether the frequency found in each category is different from the frequency that would be expected by chance.

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Continuous variable (Data)

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A variable that can take on any value between two specified points.

e.g. weight

Front 6

Correlation

Back 6

The degree of association between two variables

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Degrees of freedom (df)

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The number of quantities that are unknown minus the number of independent equations linking these unknowns; a function of the number in the sample. Represents the freedom of score's value to vary given what is known about the other scores and the sum of scores; often df=N-1.

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Descriptive statistics

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Statistical methods used to describe and summarize sample data. Includes measures of central tendency, such as, mean, median, and mode; measures of variability, such as range and standard deviation, and some correlation techniques, such as scatter plots.

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Dichotomous variable

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A nominal variable that has two categories. A variable that has only two true values, such as true or false, male or female.

e.g. male/female

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Factor Analysis

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A type of validity that uses a statistical procedure for determining the underlying dimensions or components of a variable.

Front 11

Fisher's exact probability test

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A test used to compare frequencies when samples are small and expected frequencies are less than six in each cell.

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Frequency distribution

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Descriptive statistical method for summarizing the occurrences of events under study. The number of times each event occurs is counted.

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Inferential Statistics

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Procedures that combine mathematical processes and logic to test hypotheses about a population with the help of sample data. Used to analyze the data collected, test hypotheses, and answer the research questions in a study.

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Interval measurement

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Level uses to show rankings of events or objects on a scale with equal intervals between numbers but with an arbitrary zero.

e.g. centigrade temperature

Front 15

Levels of measurement

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Categorization of the precision with which an event can be measured (nominal, ordinal, interval, and ratio). It is determined by the nature of the object or event being measured. There are 4 levels: nominal, ordinal, interval, and ratio.

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Level of significance (alpha level)

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The risk of making a type I error, set by the researcher before the study begins. The probability of rejecting a true null hypothesis.

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Mean

Back 17

A measure of central tendency; the arithmetic average of all scores. Add all the values in a distribution and divide by the total number of values.

Front 18

Measures of central tendency

Back 18

Descriptive statistical procedure that describes the average member of a sample (mean, median, and mode). Describes a pattern of responses among a sample.

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Measures of variability

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Descriptive statistical procedure that describes how much dispersion there is in sample data. It answers the questions, "Is the sample homogenous or heterogenous?" "Is the sample similar or different?"

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Median

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A measure of central tendency; the middle score. Best used when data is skewed.

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Measurement

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The standardized method of collecting data. The process of assigning numbers to variables or events according to rules.

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Modality

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The number of peaks in a frequency distribution. The number of modes contained in a distribution. Most often used with nominal data but can be used with all levels of measurements.

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Mode

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A measure of central tendency; the most frequent score or results. The most frequent value in distribution.

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Multiple analysis of variance (MANOVA)

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A test used to determine differences in group means; used when there is more than one dependent variable.

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Multiple regression

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Measure of the relationship between one interval level dependent variable and several independent variables. Canonical correlation is used when there is more than one dependent variable.

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Multivariate statistics

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A statistical procedure that involves two or more variables.

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Nominal measurement

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Level used to classify objects or events into categories without any relative ranking.

e.g. gender, hair color

Front 28

Nonparametric statistics

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Statistics that are usually used when variables are measured at the nominal or ordinal level because they do no estimate population parameters and involve less restrictive assumptions about the underlying distribution. Usually are applied when the variables have been measured on a nominal or ordinal scale or when the distribution of scores is severely skewed.

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Normal curve

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A curve that is symmetrical about the mean and is unimodal.

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Null hypothesis

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A statement that there is no relationship between the variables and that any relationship between the observed is a function of chance or fluctuations in sampling.

Front 31

Ordinal measurement

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Level used to show rankings of events or objects; numbers are not equidistant, and zero is arbitrary.

e.g. class ranking

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Parameter

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A characteristic of a population.

Front 33

Parametric statistics

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Inferential statistics that involve the estimation of at least one population parameter; require measurement at the interval level or above, and involve assumptions about the variables being studied. These assumptions usually include the fact that the variable is normally distributed.

Front 34

Pearson correlation coefficient (Pearson r; Pearson Product moment correlation coefficient)

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A statistic that is calculated to reflect the degree of relationship between two interval level variables.

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Percentile

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Represents the percentage of cases a given score exceeds.

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Probability

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The probability of an event's long-run relative frequency in repeated trials under similar conditions.

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Range

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A measure of variability; difference between the highest and lowest scores in a set of sample data. The simplest but most unstable measure of variability.

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Ratio

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The highest level of measurement that possesses the characteristics of categorizing, ordering, and ranking, and also has an absolute or natural zero that has empirical meaning.

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Ratio Measurement

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Level that ranks the order of events or objects, and that has equal intervals and an absolute zero. The number represents the actual amount of property the object possesses.

e.g. height, weight

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Sampling error

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The tendency for statistics to fluctuate from one sample to another.

Front 41

Scientific hypothesis

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The researcher's expectation about the outcome of a study; also known as research hypothesis.

Front 42

Standard deviation (SD)

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A measure of variability; measure of average deviation of scores from the mean. The most frequently used measure of variability, and it is based on the concept of the normal curve. It is a measure of average deviation of the scores from the mean and as such should be reported with the mean.

Front 43

Statistics

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A descriptive index for a sample such as a sample mean or a standard deviation. A characteristic of a sample.

Front 44

t statistics

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Commonly used in nursing research; it tests whether two group means are more different than would be expected by chance. Groups may be related or independent.

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Type I error

Back 45

The rejection of a null hypothesis that is actually true.

i.e. accepts the premise that there is a difference when actually there is no difference between groups.

Front 46

Type II error

Back 46

The acceptance of a null hypothesis that is actually false.

i.e. accepts the premise that there is no difference between the groups when a difference actually exists.