Discuss the following:
Ttest (1 of 2)
Difference testing is used primarily to identify if there is a detectable difference between products, services, people, or situations.
These tests are often conducted in business situations to:
• Ensure a change in formulation or production introduces no significant change in the end product or service.
• Substantiate a claim of a new or improved product or service
• Confirm that a new ingredient/supplier does not affect the perceived attributes of the product or service.
• Track changes during shelf life of a product or the length of time of a service.
Differences Between Two Independent Sample Means:
Coke vs. Pepsi. Independent sample ttests are used to compare the means of two independently sampled groups (ex., do those drinking Coke differ on a performance variable, or the numbers of cans consumed in one week) compared to those drinking Pepsi. The individuals are randomly assigned to the Coke and Pepsi groups. With a confidence interval of ≤.05 (corresponding probability level of 95%) the researcher concludes the two groups are significantly different in their means (average consumption rate of Coke and Pepsi over a one week period of time) if the ttest value meets or exceeds the required critical value. If the t value does not meet the critical t value required then the research investigator simply concludes that no differences exist. Further explanation is not required. Presented below is a more useable situation.
Using the raw data and formula above to calculate the actual ttest value, when calculated properly, is 2.43. Always remember that S = Standard deviation and that the mean is oftentimes shown by the capital letter M rather than a bar mark over a capital X. By going to the appropriate ttables in your textbook find the critical value for t at the .05 confidence interval. The value you should find is 1.761
Assignment : TTest
Drawn for the ttest statistical process is only as good as the research question asked and the null hypothesis formulated. Ttests are only used for two sample groups, either on a pre posttest basis or between two samples (independent or dependent). The ttest is optimized to deal with small sample numbers which is often the case with managers in any business. When samples are excessively large the t test becomes difficult to manage due to the mathematical calculations involved.
Calculate the "t" value for independent groups for the following data using the formula presented in the module. Check the accuracy of your calculations. Using the raw measurement data presented above, determine whether or not there exists a statistically significant diference between the salaries of female and male human resource managers using the appropriate ttest. Develop a research question, testable hypothesis, confidence level, and degrees of freedom. Draw the appropriate conclusions with respect to female and male HR salary levels. Report the required "t" critical values based on the degrees of freedom. Your answer must be 23 pages.
Salary Level 
Female HR Directors 
Male HR Directors 
$50,000 
$58,000 
$75,000 
$69,000 
$72,000 
$73,000 
$67,000 
$67,000 
$54,000 
$55,000 
$58,000 
$63,000 
$52,000 
$53,000 
$68,000 
$70,000 
$71,000 
$69,000 
$55,000 
$60,000 
*Do not forget what we all learned in high school about "0"s
