A researcher would like to examine how the chemical tryptophan, contained in foods such as turkey, can affect mental alertness. A sample of n = 9 college students is obtained and each student’s performance on a familiar video game is measured before and after eating a traditional Thanksgiving dinner including roast turkey. The average score dropped by M = 14 points after the meal with SS = 1152 for the difference scores. A. Is there is significant difference in performance before eating versus after eating? Use a two-tailed test with α = .05. SMD = ___________________________ tcritical = ________________________ tcalculated = ________________________ Decision = _______________________ B. Compute r2 to measure the size of the effect. r2 = _____________________________ C. Write a sentence demonstrating how the outcome of the test and the measure of effect size would appear in a research report.
Continuous Probability Distributions
Probability distributions are of two types, which are continuous probability distributions and discrete probability distributions. A continuous probability distribution contains an infinite number of values. For example, if time is infinite: you could count from 0 to a trillion seconds, billion seconds, so on indefinitely. A discrete probability distribution consists of only a countable set of possible values.
Normal Distribution
Suppose we had to design a bathroom weighing scale, how would we decide what should be the range of the weighing machine? Would we take the highest recorded human weight in history and use that as the upper limit for our weighing scale? This may not be a great idea as the sensitivity of the scale would get reduced if the range is too large. At the same time, if we keep the upper limit too low, it may not be usable for a large percentage of the population!
A researcher would like to examine how the chemical tryptophan, contained in foods such as turkey, can affect mental alertness. A sample of n = 9 college students is obtained and each student’s performance on a familiar video game is measured before and after eating a traditional Thanksgiving dinner including roast turkey. The average score dropped by M = 14 points after the meal with SS = 1152 for the difference scores.
A. Is there is significant difference in performance before eating versus after eating? Use a
two-tailed test with α = .05.
SMD = ___________________________
tcritical = ________________________
tcalculated = ________________________
Decision = _______________________
B. Compute r2 to measure the size of the effect.
r2 = _____________________________
C. Write a sentence demonstrating how the outcome of the test and the measure of effect
size would appear in a research report.
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