Lab reports

Instructions: A. Select one interval or ratio level variable to analyze. Notes: The variable selected cannot be one of the variables used for class demonstration. Duration variables (i.e., DUR26) are a good choice for this lab exercise. B. In SPSS, run your descriptive statistics on your variable, including a histogram. Analyze Descriptive Statistics Explore on the variable, including a histogram. Make sure that you check the Outliers box in the Statistics window. Note: Use this analysis for your Descriptives. It provides the Extreme Values (outliers) output, useful for identifying if filtering is needed or not! Address the following: 1. Identify the variable used. Identify the mean, and standard deviation of the variable. 2. Is this distribution normal in terms of symmetry and shape? What statistics tell you if your distribution is normal? Provide the values of the statistics, and explain how you know whether your variable is normally distributed or not. a) Note: if your variable is normally distributed, provide this analysis, and select a second variable to use for the lab assignment. 3. Run a transformation on your variable to create a normal distribution. Provide the formula used to transform the variable. Hints: Is your data positively or negatively skewed? Does your variable range include 0? 4. Re-run your Descriptives. Is this new distribution normal in terms of symmetry and shape? Provide the values of the statistics, and explain how you know whether your variable is normally distributed or not. 5. Are there any extreme frequencies which may be affecting your new distribution? a) If yes, filter the original non-transformed variable, and provide the filtering formula. Hint: Select cases. Additional hint: Look at your original histogram! Re-run your Descriptives on the transformed variable. Is this new distribution normal in terms of symmetry and shape? Provide the values of the statistics, and explain how you know whether your variable is normally distributed or not. b) If you do not think there are any extreme frequencies, explain your reasoning. 6. Are there any outliers that fall outside of the normal distribution? Identify the case numbers of the highest and lowest outliers. (Hint: look at the Extreme Values output to identify outliers!) Your lab report must include the SPSS output, including the Descriptives box, Extreme Values box, and histogram for the original, transformed, and filtered (if necessary) variables.