QUESTION IMAGE
Question
- a researcher reports an f - ratio with df = 4, 62 from an independent - measures research study.
a. how many treatment conditions were compared in the study?
b. what was the total number of participants in the study?
c. use appendix b to find the critical value for f. use α =.05.
d. what is the critical region for α =.01?
Part (a)
Step1: Recall df between groups formula
For an independent - measures ANOVA, the degrees of freedom between groups (treatment conditions) is given by \(df_{between}=k - 1\), where \(k\) is the number of treatment conditions.
Step2: Solve for k
We know that \(df_{between}=4\). From the formula \(df_{between}=k - 1\), we can solve for \(k\) by adding 1 to both sides of the equation. So \(k=df_{between}+ 1\).
Substituting \(df_{between} = 4\) into the formula, we get \(k = 4+1=5\).
Step1: Recall df within groups formula
For an independent - measures ANOVA, the degrees of freedom within groups is given by \(df_{within}=N - k\), where \(N\) is the total number of participants and \(k\) is the number of treatment conditions. We know that \(df_{within}=62\) and from part (a) we found that \(k = 5\).
Step2: Solve for N
We start with the formula \(df_{within}=N - k\). Rearranging the formula to solve for \(N\), we get \(N=df_{within}+k\).
Substituting \(df_{within}=62\) and \(k = 5\) into the formula, we have \(N=62 + 5=67\).
Step1: Identify df values
We have \(df_{between}=4\) (numerator degrees of freedom) and \(df_{within}=62\) (denominator degrees of freedom), and \(\alpha = 0.05\).
Step2: Use F - distribution table
When we look up the critical value for an F - ratio in the F - distribution table, with \(df_1 = 4\) (numerator) and \(df_2=62\) (denominator) and \(\alpha=0.05\). Since 62 is not a common value in some tables, we can use the approximation for large \(df_2\) or use the fact that as \(df_2\) increases, the critical value approaches the value for \(df_2=\infty\). Looking at the F - table for \(\alpha = 0.05\), \(df_1 = 4\) and \(df_2=\infty\), the critical value is approximately 2.41. (If we use a more precise method or a table that includes \(df_2 = 60\) (since 62 is close to 60), for \(df_1 = 4\) and \(df_2=60\), the critical value is also approximately 2.41)
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The number of treatment conditions is \(\boldsymbol{5}\).