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Hypothesis Testing - APA format results for t test

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A researcher studied the effect of television violence on concentration of a particular blood chemical. In this study, 40 participants were measured over a period of an hour prior to watching a violent show and then immediately after. In the results section, the researcher writes: "There was a significant decline in blood concentration from a mean of 13.41 (SD=2.48) to 12.38 (SD=2.69), t(39)=3.38, p<.01 (one tailed)."

Can you explain this result (including the underlying logic of the computations) to me who understands hypothesis testing involving a single sample and a known population, but knows nothing about t tests?

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Please find the formatted solution of your posting in the attached file. I hope it will help you to understand the topic. Thanks!



Here we have two samples such as

Prior watching a violent show and after watching a violent show

(*Example of how to arrange the data is found in the ...

Solution Summary

This solution is comprised of a detailed explanation for the results of t test. Full description is given including mean and standard deviation, level of significance, t test statistics value, P-value, decision about rejecting or not rejecting the null hypothesis along with concluding remarks are given in the solution.

See Also This Related BrainMass Solution

Statistics: Time to solve Duncker (1945) problem to mount a candle on a wall

20. In a classic study of problem solving, Duncker (1945) asked participant to mount a candle on a wall in an upright position so that it would burn normally. One group was given a candle, a book of matches, and a box of tacks. A second group was given the same items, except that the tacks and the box were presented separately as two distinct items. The solution to the problems involves using the tacks to mount the box on the wall, creating a shelf for the candle. Duncker reasoned that the first group of participants would have trouble seeing a "new" function for the box (as a shelf) because it was already serving a function (holding tacks). For each participant, the amount of time to solve the problem was recorded. Data similar to Duncker's are as follows:

Time to solve Problem (in seconds)
Box of tacks
94 Tacks and Box separate

n = 5 n = 5
M = 119.20 M = 43.20
SS = 2746.80 SS = 1066.80

Following the four steps outlined below, test the null hypothesis that there are no significant differences between the two groups.

1) State the null and alternative hypothesis and an alpha level of &#945; = .01, two-tailed, to test the hypothesis (use both the appropriate symbol and words).
2) Calculate the degree of freedom for an independent measure test and locate the critical region (using the provided table; df=df1+df2)
3) Calculate the appropriate t statistic for the problem
4) Make a decision and write an APA-style result section for your findings. (do the data indicate a significant difference between the two conditions)?
Make sure that you show all computations and writer a complete APA result section for the question.


df=df1+df2 = (n1-1) + (n2-1)
See attached file for complete list of formulas.

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