Practice Statistics Questions

Activity 1- ANOVA Practice

Test 1 – Comparing Spreadsheet Skills (SS) among 3 Subject Area Groups (Subject)

  1. Do you think the sample sizes for each groups are high enough? Please explain.
  2. Are variances homogenous (in other words is the spread of values for each group similar)? Please explain.
  3. Is there a significant difference among the three groups? Justify your answer with an F value and p value?
  4. Summarize the multiple comparisons test by filling in the table below.

Table 1. One-Way ANOVA for Subject Area and Spreadsheet Skills

Group 1 Mean (SD) / Group 2 Mean (SD) / Mean Diff / p value
Example1 23.1 (3.4) / Example2 20.1 (3.4) / 3.0 / p < .05
Example 1 23.1 (3.4) / Example3 22.1 (3.4) / 1.0 / n.s.

n.s. stands for not significant

Test 2 – Web-Page Design Skills Skills (WBPG) among 3 Subject Area groups (Subject)

  1. Are variances homogenous (in other words is the spread of values for each group similar)? Please explain.
  2. Is there a significant difference among the three groups? Justify your answer with an F value and p value?
  1. Summarize the multiple comparisons test by filling in the table below.

Table 2. One-Way ANOVA for Subject Area and Spreadsheet Skills

Group 1 Mean (SD) / Group 2 Mean (SD) / Mean Diff / p value
Example1 23.1 (3.4) / Example2 20.1 (3.4) / 3.0 / p < .05
Example 1 23.1 (3.4) / Example3 22.1 (3.4) / 1.0 / n.s.

n.s. stands for not significant

Activity 2- Correlation Practice

Run a correlation analysis for the following variables:

  • Self-Efficacy (SelfEff_Att)
  • Database Skills (DB)
  • Webpage Skills (WBPG)
  • Science Skills (SCI)

Sample format for communicating a correlation result

  • Variable A is significantly and positively correlated with Variable B (r=0.45, p< .01)
  • Variable A is significantly and negatively correlated with Variable B (r=-0.25, p< .05)
  • Variable A is not significantly correlated with Variable B (r=0.12, n.s.)
  1. Communicate the statistical relationship between self-efficacy and database skills in a sentence.
  1. Communicate the statistical relationship between self-efficacy and webpage skills in a sentence.
  1. Communicate the statistical relationship between self-efficacy and webpage skills in a sentence.
  1. After, looking at the results, do you think self-efficacy, to a certain extent, causes improved database skills in the long run? Please explain

Cohen’s D for Correlation Tests (sort of)

To calculate the meaning of a correlation, simply square it. For example, if a correlation between age and height is 0.5, the amount of variance it predicts for the other variable is 0.5 * 0.5 or 0.25. In other words, the meaningful amount that age and height are related is 0.25.

  1. Are the correlations reported in questions 1 to 3 above meaningful? Please justify.

Activity 3 –Internal Reliability

Run an internal reliability analysis for the confidence scale items (PC3, PC4, PC5, PC6, PC7)

  1. What is the total number of valid case for this analysis?
  2. What is Chonbach’s Alpha? Would you conclude this scale as good internal reliability? Explain.
  3. Which item in the scale has the highest mean? Report both mean and standard deviation for this item.
  4. Which item in the scale has the lowest mean? Report both mean and standard deviation for this item.