In: Statistics and Probability
. (Education) A researcher would like to know whether there is a consistent, predictable relationship between verbal skills and math skills for high school students. A sample of 300 students is obtained and each student is given a standardized English test and a standardized math test. Based on the test results, students are classified as high, medium, or low for verbal skills and for math skills. The results are summarized in the following frequency distribution:
verbal skills
high | medium | low | |
high | 20 | 48 | 22 |
medium | 23 | 62 | 35 |
low | 17 | 40 | 33 |
Math skills
Based on these results, can the researcher conclude that there is a significant relationship between verbal skills and math skills at the 10% level of significance?
Null hypothesis: Ho: verbal skills and math skills are independent
Alternate hypothesis: HA: verbal skills and math skills are related
degree of freedom(df) =(rows-1)*(columns-1)= | 4 | |
for 4 df and 0.1 level , critical value χ2= | 7.779 | |
Decision rule : reject Ho if value of test statistic X2>7.779 |
Applying chi square test of independence: |
Expected | Ei=row total*column total/grand total | high | medium | low | Total |
high | 18.000 | 45.000 | 27.000 | 90.00 | |
medium | 24.000 | 60.000 | 36.000 | 120.00 | |
low | 18.000 | 45.000 | 27.000 | 90.00 | |
total | 60.00 | 150.00 | 90.00 | 300.00 | |
chi square χ2 | =(Oi-Ei)2/Ei | high | medium | low | Total |
high | 0.222 | 0.200 | 0.926 | 1.3481 | |
medium | 0.042 | 0.0667 | 0.0278 | 0.1361 | |
low | 0.056 | 0.5556 | 1.3333 | 1.9444 | |
total | 0.3194 | 0.8222 | 2.2870 | 3.429 | |
test statistic X2 = | 3.429 |
since test statistic does not falls in rejection region we fail to reject null hypothesis | ||||
we do not have have sufficient evidence to conclude that verbal skills and math skills are related |