Chapter 10 Analyzing Data Flashcards
Analysis of variance (ANOVA)
A parametric procedure used to test whether there is a difference among three group means.
Chi-square
- A nonparametric procedure used to assess whether a relationship exists between two nominal level variables; symbolized as χ².
- The most commonly reported nonparametric statistic (i.e., not normally distributed) to determine whether groups are different.
- Compares the frequency of an observed occurrence (actual number in each category) with the frequency of an expected occurrence (based on theory or past experience).
Correlation
A measure that defines the relationship between two variables.
Descriptive statistics
- Statistics that describe, organize, and summarize data.
2. Based on frequency and includes measures of central tendency and measures of dispersion.
Homogeneity of variance
Situation in which the dependent variables do not differ significantly between or among groups.
Inferential statistics
- Statistics that generalize findings from a sample to a population. Based on parameters.
- Two types: Parameter estimation and hypothesis testing.
Level of confidence
Probability level in which the research hypothesis is accepted with confidence. A 0.05 level of confidence is the standard among researchers (this means that researchers are willing to accept statistical significance occurring by chance 5 times out of 100).
Mean
- A measure of central tendency calculated by summing a set of scores and dividing the sum by the total number of scores; also called the average. Represented by x̄ or M.
- The calculation takes into account each score in the distribution. Easily used in more advanced statistical analyses.
- A precise, stable, and reliable measure, but it is sensitive to outliers (the mean will be “pulled” in the direction of extreme values).
Measures of central tendency
- Descriptive statistics that describe the location or approximate center of a distribution of data.
- Three types: Mean, median, and mode.
- The specific measure is chosen based on the level of measurement, shape, or form of the distribution of data and research objective.
Measures of dispersion
- Descriptive statistics that depict the spread or variability among a set of numerical data.
- Three types: Range, variance, and standard deviation. (Also used, but less frequent: Percentile and interquartile range.)
Median
- A measure of central tendency that represents the middle score or midpoint in a distribution. Represented by Mdn; sometimes known as the 50th percentile.
- An ordinal statistic based on ranks: Calculated by first arranging the scores in rank order. If there is an odd number of scores, the median is the middle score. If there is an even number of scores, the median is the point halfway between the two middle scores (and thus would not be a score that appears in the distribution).
- Does not take into account each score in the distribution and is not sensitive to extreme scores.
Mode
- The score or value that occurs most frequently in a distribution; a measure of central tendency used most often with nominal-level data.
- There may be more than one mode for any distribution of scores - data with a single mode are called unimodal and data with two modes are called bimodal.
- Can be applied to any set of data at the nominal, ordinal, or interval/ratio level of measurement.
- Easily identified when a frequency distribution is used.
Negative correlation
Correlation in which high scores for one variable are paired with low scores for the other variable.
Outlier
Data point isolated from other data points; extreme score in a data set.
Parameter
Numerical characteristic of a population (e.g., population mean, population standard deviation).
Positive correlation
Correlation in which high scores for one variable are paired with high scores for the other variable, or low scores for one variable are paired with low scores for the other variable.