Math Problem Statement

Answer this

You have run an ANOVA NHST with g = 8 groups and n = 6 observations per group. Fill in the rest of the ANOVA table and calculate various statistical measures, including the F-test statistic, effect size (η²), and pooled standard deviation.

Solution

To solve this ANOVA problem step by step, let’s break it down:

Known Data:

  • Total Sum of Squares (SS Total): 2,870.02,870.0
  • Model Sum of Squares (SS Model): 1,091.91,091.9
  • Degrees of Freedom for Groups (df Model): g1=81=7g - 1 = 8 - 1 = 7
  • Degrees of Freedom for Residuals (df Residual): g(n1)=8(61)=40g \cdot (n - 1) = 8 \cdot (6 - 1) = 40
  • Total Degrees of Freedom (df Total): gn1=861=47g \cdot n - 1 = 8 \cdot 6 - 1 = 47

From this information:

  • SS Residual = SSTotalSSModel=2,870.01,091.9=1,778.1SS Total - SS Model = 2,870.0 - 1,091.9 = 1,778.1

Fill the ANOVA Table:

  1. Model Mean Square (MS Model):
    MSModel=SSModeldfModel=1,091.97155.986MS Model = \frac{SS Model}{df Model} = \frac{1,091.9}{7} \approx 155.986

  2. Residual Mean Square (MS Residual):
    MSResidual=SSResidualdfResidual=1,778.14044.453MS Residual = \frac{SS Residual}{df Residual} = \frac{1,778.1}{40} \approx 44.453

Test Statistic FF:

F=MSModelMSResidual=155.98644.4533.51F = \frac{MS Model}{MS Residual} = \frac{155.986}{44.453} \approx 3.51

Effect Size (η2\eta^2):

η2=SSModelSSTotal=1,091.92,870.00.3803\eta^2 = \frac{SS Model}{SS Total} = \frac{1,091.9}{2,870.0} \approx 0.3803

Pooled Standard Deviation (σe\sigma_e):

The pooled standard deviation is the square root of MSResidualMS Residual:
σe=MSResidual=44.4536.67\sigma_e = \sqrt{MS Residual} = \sqrt{44.453} \approx 6.67

P-value:

To determine the P-value, the FF-distribution must be consulted with df1=7df_1 = 7 and df2=40df_2 = 40. Based on these values and F3.51F \approx 3.51, we can find the approximate pp-value using an FF-table or software. I can confirm this more precisely if you prefer!


Let me know if you need any clarifications or more details! 😊

Questions for Further Practice:

  1. How would the results change if the number of groups gg increased while nn remained constant?
  2. What assumptions are necessary for performing an ANOVA test?
  3. How do you interpret a small η2\eta^2 effect size?
  4. What are post-hoc tests, and when should they be applied after an ANOVA?
  5. Can you calculate the confidence intervals for group means using the MSResidualMS Residual?

Tip:

Always double-check degrees of freedom calculations to ensure the table is consistent!

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Math Problem Analysis

Mathematical Concepts

Analysis of Variance (ANOVA)
Statistical Hypothesis Testing
Degrees of Freedom
Effect Size

Formulas

df_Model = g - 1
df_Residual = g * (n - 1)
MS_Model = SS_Model / df_Model
MS_Residual = SS_Residual / df_Residual
F = MS_Model / MS_Residual
η² = SS_Model / SS_Total
σ_e = sqrt(MS_Residual)

Theorems

F-Distribution
Partitioning of Total Variance

Suitable Grade Level

Undergraduate (Statistics/Math Major)