U03a1

For this assignment, see the unit 3 model example below. The model example provides the format and organization that should be used for all subsequent data analysis and interpretation assignments. The model provides an example of the narrative report and format that will be required for all subsequent data analysis assignments. For all subsequent units, the model example will only be provided after the assignment is submitted.

For this week's assignment, you will analyze the data and substitute your results and interpretation into the model example. The task will be to complete a one-way ANOVA with the same independent variable (ENGL) as in the model example, but with a different dependent variable (GPA instead of IQ). See the unit 3 model example file and the unit 3 datafile to complete this week's assignment. The Howell and Huessy datafile also will be used for additional unit assignments later in the course. This datafile is described in detail below.

Howell and Huessy (1985) reported on a study of 386 children who, during childhood, had or had not exhibited symptoms of attention deficit disorder (ADD), previously known as hyperkinesis or minimal brain dysfunction. For a more complete description of this research, see below. In 1965, teachers of all second-grade school children in a number of schools in northwestern Vermont were asked to complete a questionnaire for each of their students dealing with behaviors commonly associated with ADD. Questionnaires about these same children were again completed when they were in the fourth and fifth grades. For purposes of this data set only, those three scores were averaged to produce a score labeled ADDSC. The higher the score, the more ADD-like behaviors the child exhibited. At the end of the ninth grade and again at the end of the 12th grade, information on the performance of these children was obtained from school records. There the data offered the opportunity to examine questions about whether later behavior can be predicted from earlier behavior and to examine academically related variables and their relationships. A description of each variable follows:

• ADDSC The average of the three ADD-like behavior scores obtained in elementary school.
• SEX 1=male; 2=female.
• REPEAT 1=repeated at least one grade; 0=did not repeat a grade.
• IQ IQ obtained from a group-administered IQ test.
• ENGL Level of English in ninth grade: 1= college prep; 2 = general; 3 = remedial.
• ENGG Grade in English in ninth grade; 4 = A; 3 = B, etc.
• GPA Grade point average in ninth grade.
• SOCPROB Social problems in ninth grade: 1=yes; 0=no.
• DROPOUT 1=dropped out during high school; 0=did not drop out.

Section II--Assumptions, data screening, and verification of assumptions:

• Clearly identify and verify any assumptions and requirements underlying the use of each inferential statistical procedure.
• Systematically verify each assumption and requirement for the variables that will be used in the analysis.
• If an assumption or requirement cannot be verified with the given information, indicate what information would be needed to provide verification.
• If the assumption or requirement is not consistent with the variables in the data file, indicate what remediation might be undertaken to ameliorate the problem.
• Screen the data for out-of-bound values and outliers.

ANOVA is a parametric statistical procedure that includes several assumptions and requirements. These include

1. Random sampling.
2. Interval or ratio measurement for the dependent variable.
3. Normally distributed groups.
4. Equal variance between groups (homoscedasticity).

Based on the published results of the study conducted by Howell and Huessy, it will be assumed that the participants were randomly selected. Inspection of the dependent variable and prior practice within the research community indicates that IQ can be treated as an interval scaled variable, although this assumption is open to debate.

Table 2 below provides a descriptive summary of the distribution of IQ for each ENGL group. It can be noted that groups 1 and 2 are somewhat negatively skewed, while group 3 has a positive skewness. Likewise, groups 1 and 2 appear to have similar variances, while the variability of group 3 is greater than either group 1 or 2. All values of ENGL and IQ appear to be within an expected possible range for each variable.

Section III-Inferential procedure, hypotheses, alpha level

• State the alpha level (use .05 unless otherwise indicated).
• State the research question(s).
• State the statistical hypotheses, both null and alternative.
• Indicate what the calculated statistic will be that addresses each of the hypotheses.

Alpha level = .05

The reason question is, "Are there mean differences in IQ among the three ninth-grade English level classes?"

Ho: The mean IQs of the three ENGL groups are equal; or

Ho: µ 1 = µ 2 = µ 3

H1: The mean IQs of the three ENGL groups are not equal; or

H1: µ1 ? µ2 ? µ3

The statistical procedure that will be used to test this hypothesis is one-way ANOVA. The calculated statistical result will be an F value.

Section IV-Interpretation

• Indicate the results and interpret the meaning of the results for each inferential analysis and do this specifically for the variables that are being analyzed.
• State your conclusions, as they relate directly to the research questions and hypotheses, based on the interpretation of the results.
• Indicate any limitations or constraints regarding these conclusions.

Table 6 provides the result of the ANOVA analysis. The F of 12.850 is statistically significant at and below the .05 level. Thus, the null hypothesis is rejected and the initial conclusion is that the mean IQs of the three ENGL groups are not equal. Since there are more than two ENGL groups, additional analysis is needed to identify exactly which groups have significantly different means and how these means differ.

Table 7 indicates that all possible pairs of ENGL groups are significantly different. Table 8 shows that the College Bound English group (group 1) had a mean IQ of 111.03, while the general English classes had a mean IQ of 102.03 and the remedial English classes had a mean IQ of 95.98. Figure 3 illustrates these differences graphically.

These results might indicate that placement in ninth grade English is related to not only the student's competence in English but also to their IQ. Further information concerning how students are actually placed would be needed before any more definitive conclusions could be reached.

Price: $15.91

Solution: The downloadable solution consists of 9 pages, 691 words and 14 charts.
Deliverable: Word Document