PSYC 3002 – Week 4 Assignment 1 – t-Test
The procedure employed when we test two sample means randomly selected in such a way that scores in one sample are not influenced by the scores in the other sample is referred to as independent-samples t-test (Heiman, 2015, Pg. 142). From our study, the 30 drivers are randomly selected and divided into two independent groups of fifteen drivers assigned for 5 hours of sleep and the other 15 drivers assigned for 8 hours of sleep. All are randomly selected. We, therefore, conclude that the researcher should use an independent-sample t-test for this scenario.
Sleep hours (5 and 8 hours) would be the independent variable, while reaction time would be the dependent variable in this scenario.
The null hypothesis (Ho) for this study is; there is NO significant difference in the mean of reaction time between the drivers taking 5 hours and 8 hours of sleep. The alternative hypothesis (Ha) for this study is; there is a significant difference in the mean reaction time between the drivers taking 5 hours and 8 hours of sleep.
We would have a two-tailed test if we were not aware of the direction the score would go (Heiman, 2015, Pg. 109). The researchers from the study have predicted the direction the scores will go; therefore, a one-tailed test is appropriate for this study.
PSYC 3002 – Week 4 Assignment 1 – t-Test
The t value for this data computed using SPSS is 457.
The degree of freedom for an independent samples t-test, df = (n1 – 1) + (n2 – 1) (Heiman, 2015, Pg. 147)
Note: n1 = number of participants under condition 1 N2 = number of participants under condition 2.
From our study, n1 = 15, n2 = 15
Mathematically, (15 – 1) + (15 – 1) = 14 + 14 = 28. The degree of freedom for this
the study is 28.
The p-value obtained using SPSS is 318
Since the p-value computed using SPSS 0.318 > 0.05 level of significance, the researcher should therefore retain the null hypothesis. It is in the region of acceptance. The sample appears extremely unlikely, so the researcher should therefore retain the null hypothesis.
Since we accepted the null hypothesis, the researcher can conclude that there is no relationship between the hours of sleep by the participants and their reactions.
References
Heiman, G (2015) Behavioural Sciences STAT (2nd ed.). Stamford, CT: Cengage.
Laureate Education (Producer). (2015h). One-sample and two-sample t-tests [Video file]. Baltimore, MD: Author.
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Question
PSYC 3002 – Week 4 Assignment 1 – t-Test
Explain whether the researcher should use an independent-samples t-test or a related-samples t-test for this scenario. Provide a rationale for your decision.
Identify the independent variable and dependent variable.
Knowing the researcher believes that people who sleep less will have slower reaction times, state the null hypothesis and alternative hypothesis in words (not formulas).