Levels of data and inferential statistics

• Nominal data


  Data in separate categories without order, e.g., Obeyed/Disobeyed
• Ordinal data


  Data ordered in some way, e.g., 1st, 2nd, 3rd
• Interval data

  Data with equal intervals, no true zero, e.g., minutes, kilograms
• Ratio data


  Data on a scale with a true zero, e.g., weight, time
• Critical value table


  Table used to find if a calculated value is statistically significant
• Statistical significance


  Result unlikely due to chance, often at 5% level (0.05)
• Type I error


  Incorrectly rejecting a true null hypothesis
• Type II error


  Incorrectly accepting a false null hypothesis
• Significance Level


  Threshold for rejecting null hypothesis, e.g., 0.05
• Spearman's Rank Order Correlation Coefficient


  Measures strength of monotonic relationship between variables
• Critical Value Tables


  Reference for determining significance in statistical tests
• Chi-Square Test


  Compares observed and expected frequencies in nominal data
• Degrees of Freedom


  Number of independent values in a calculation
• Contingency Table


  Table to display frequencies of variables for analysis
• Mann Whitney U Test


  Determines differences between two independent groups
• Wilcoxon Matched Pairs Signed Ranks Test

  Evaluates differences between two related groups
• Parametric Tests


  Statistical tests assuming normal distribution and equal variances
• Stratified Sample


  Sample divided into subgroups for representation
• Dependent Variable


  Variable influenced by independent variable changes
• Extraneous Variable


  Uncontrolled variable that may affect study outcomes
• Mean


  Average value of a set of numbers
• Standard Deviation


  Measure of data dispersion around the mean