Variables

Variables

1. Independent Variables

   • Things you can manipulate or control.Participant age, Design you testing

2. Dependent Variables

   • Things you can measure. Success rate, number of errors, completion time

3. Data Types

   • Nominal Data
     • AKA Categorical. Unordered groups or Categories. We can say they are different and not better than the other. Examples Windows or Mac user Male or Female Geographical region
       • Descriptive Statistics 45% are female 95% were successful
   • Ordinal Data
     • Ranked Data. Ordered groups or Categories. Organized data. Intervals between measurements are not meaningful. Examples User rates a webiste Excellent, Good, Poor
       • Descriptive Statistics 20% Excellent, 30% Poor, 50 5 Good
     • Nonparametrics test
       • Chi Square test
   • Interval Data
     • Continuous Data. Intervals between measurements are meaningful. NO ZERO POINT Examples Temperature System Usability Scale (UX) Score 0-100. Distance beween points have meaning
       • Descriptive Statistics Average, Standard Deviation. Inferential Statistics Generalize about population
     • Comparing means
       • Independent Sample
         • Compare with int e SAME SET of user over different things/products
           • Confidence intervals. Do they overlap?
       • Paired Samples
         • Compare the SAME group of users on different things/products
           • Use t Test
   • Ratio Data
     • Same as Interval Data. ABSOLUTE ZERO POINT. Zero has some meaning Eg. age, height, weight UX Example Time Zero seconds left to complete task.
       • Descriptive Statistics Average, Standard Deviation. Inferential Statistics Generalize about population
         • Statistics
           • Descriptive Statistics
             • Describes the data. Says nothing about the population.
               • Measures of Central Tendency
                 • A single number that in some way represents a set of numbers
                   • Mean - The average.
                   • Median - middle number (Order data set).
                   • Mode - Most frequent number
               • Measure of Variability
                 • How much the data is spread/dispersed across a range of values
                   • Range - distance between minimum and maximum values (outlier).
                   • Variance - How spread out the data are relative to the mean.
                     • Data point minus the mean. Then square the result. Sum up all the values . Then divide by total number of values - 1
                   • Standard Deviation - The square root of the variance
               • Confidence Intervals
                 • An estimate of a range of values that includes the true population value for a statistic
                   • Sample Size
                   • Standard deviation
                   • Alpha level to use
           • Inferential Statistics
             • Draw or infer some conclusion about a larger population.
           • Correlation
             • xamine the relation ship between 2 variables
               • Use Scatter Plot. TREND LINE
           • Visualizing Data
             • Graphical way to illustrate data
               • Bar Graph
                 • Continuous Data for discrete item / categories
               • Line Graph
                 • Used to show trends over time. Continuous Data
               • Scatter Plots
                 • Show pairs of values
                   • Relationship between 2 variables
               • Pie Chart
                 • Part or percentages of a whole
                   • Show proportions
               • Stacked bar
                 • Multiple Pie charts in one bar