Chapter 12 Vocab Flashcards
alpha level
probability of making a type I error; typically designated as 0.05 or 0.01 at the end of the tail in a distribution
amodal
a data set that does not have a mode
analysis of variance
(ANOVA) an inferential statistical test used when the level of measurement is interval or ratio and more than two groups are being compared
bimodal
a data set with two modes
bivariate analysis
the use of statistics to describe the relationship between two variables
Chi square
a common statistic used to analyze nominal and ordinal data to find differences between groups
coefficient of variation
a percentage used to compare standard deviations when the units of measure are different or when the means of the distributions being compared are far apart
confidence intervals
ranges established around means that estimate the probability of being correct
correlation coefficients
an estimate, ranging from 0.00 to +1.00, that indicates the reliability of an instrument; a statistic used to describe the relationship between two variables
degrees of freedom
a statistical concept used to refer to the number of sample values that are free to vary
descriptive statistics
collection and presentation of data that explain characteristics of variables
direction
the way two variables convary
heterogeneous
the degree to which elements are diverse or not alike
homogeneous
elements that share many common characteristics
independent t test
a variation of the t test used when data values vary independently from one another
inferential statistics
analysis of data as the basis for prediction related to the phenomenon of interest
kurtosis
the peakedness or flatness of a distribution of data
magnititude
the magnitude of the relationship existing between two variables
mean
the mathematical average calculated by adding all of the data values and then dividing by the total number of values
measures of central tendency
measures (e.g. mean, median, mode) that provide information about the typical case
measures of variability
measures providing information about how different data are within a set; measures of dispersion
median
the point at the center of a data set
modality
the number of modes found in a data distribution
mode
the most frequently occurring value in a data set
multiple regression
an inferential statistical test used to describe the relationship of three or more variables
negatively skewed
a distribution when the mean is less than the median and the mode; the longer tail is pointing to the left
nonparametric
inferential statistics involving nominal or ordinal level data to infer to the population
nonsignificant
when critical values fall within three standard deviations of the mean; findings do not support the research hypothesis, findings that support the null hypothesis
normal distribution
a representation of data having a distinctive bell-shaped curve and is symmetric about the mean
parametric
inferential statistical tests involving interval- or ratio-level data to infer to the population
pearson’s r
an inferential statistic used when two variables are measured at the interval or ration level; Pearson product–moment correlation
percentage distributions
descriptive statistic used to group data to make results more comprehensible
percentile
a measure or rank representing the percentage of cases that a given value exceeds
population parameters
characteristics of a population inferred from characteristics of a sample
position of the median
calculated by using the formula (n+1)/2, where n is the number or data values in the set
positively skewed
a distribution in which the mean is greater than the median and the mode; longer tail is pointing to the right
probability
likelihood or chance that an event will occur in a situation
range
the difference between the maximum and minimum values in a data set
sample statistics
numerical data describing characteristics of the sample
sampling distribution
a theoretical distribution representing an infinite number of samples that can be drawn from a population
sampling error
error resulting when elements in the sample do not adequately represent the population
semiquartile range
the range of the middle 50% of the data
skewed
an asymmetrical distribution of data
standard deviation
a measure of variability used to determine the number of data values falling within a specific interval in a normal distribution
statistically significant
when critical values fall in the tails of normal distributions; when findings did not happen by chance
statistics
describes the numerical outcomes and probabilities derived from calculations on raw data
Statistics
describes the branch of mathematics that collects, analyzes, interprets, and presents numerical data in terms of samples and populations
t statistic
inferential statistical test to determine if a statistically significant difference between the groups exists
tailedness
the degree to which a tail in a distribution is pulled to the left or to the right
type I error
occurs when the researcher rejects the null hypothesis when it should have been accepted
type II error
occurs when researchers inaccurately conclude that there is no relationship between the independent and dependent variables when an actual relationship does exist
unimodal
a data set with one mode such as a normal distribution
univariate analysis
the use of statistical tests to provide information about one variable
z scores
standardized units used to compare data gathered using different measurement scales
rule of 68-95-99.7
Rule stating that for every sample 68% of the data will fall within one standard deviation of the mean; 95% will fall within two standard deviations of the mean; 99.7% of the data will fall within three standard deviations of the mean
correlated t test
a variation of the t test used when there is only one group or when the groups are related; paired t test
