The following table summarizes the results of a study on SAT prep courses, compa

Tyra

Tyra

Answered question

2021-10-14

The following table summarizes the results of a study on SAT prep courses, comparing SAT scores of students in a private preparation class, a high school preparation class, and no preparation class. Use the information from the table to answer the remaining questions. 
TreatmentNumber of ObservationsSample MeanSum of Squares (SS)Private prep class60680265,500.00High school prep class60650276,120.00No prep class60635302,670.00 
Using the data provided, complete the partial ANOVA summary table that follows (Hint: T, the treatment total, can be calculated as the sample mean times the number of observations G, the grand total, can be calculated from the values of T once you have calculated them.) 
SourceSum of Squares (SS)dfMean Square (MS)Between treatments   Within treatments    
ANOVA summary tables typically have a "Total" row not induded in the partial table you just completed. Which of the following is a possible reason for induding this row? 
a) The MStal is used in the calculation of the F test statistic. 
b) The SStal is used in the calculation of the F test statistic. 
c) The total sums of squares is the sometimes called the "error term" 
d) The SStotal is sometimes easier to calculate than. SSbetween Since SSwithin+SSbetween=SStotal, you can use SStotal to calculate SSbetween.
In ANOVA, the F test statistic is the ? of the between-treatments variance and the within-treatments variance. the value of the F test statistic is ? 
When the null hypothesis is true, the F test statistic is ? When the null hypotesis is false, the F test statistic is most likely ? In general, you should reject the null hypotesis for.

Answer & Explanation

faldduE

faldduE

Skilled2021-10-15Added 109 answers

Step 1 
Let X1 be the SAT scores of students in a private preparation class. 
Let X2 be the SAT scores of students in a high school preparation class. 
Let X3 be the SAT scores of SAT scores of students in no preparation class. 
From the available information, 
n1=60, x1=680, SS1=265500 
n2=60, x2=650, SS2=276120 
n3=60, x3=635. SS3=302670 

Size of each group/treatment, n=n1=60 
Number of treatments, k=3 
x=1ki=1kxi=13{x1+x2+x3}=13{680+650+635}=655 
Between sum of squares, 
SSbetween=i=1kn1(xix)2=n1(x1x)2+n2(x2x)2+n3(x3x)2 
=(60)(680655)2+(60)(650655)2+(60)(635655)2 
=63000 
Within sum of squares, 
SSwith=i=1kSS1+SS2+SS3 
=265500+276120+302670 
=844290 
Degrees of freedom: 
dfbetween=k1=31=2 
 

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