please underline according to the picture! Attempts: Score: /4 Aa Aa 4. An alter
ID: 3368303 • Letter: P
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please underline according to the picture!
Attempts: Score: /4 Aa Aa 4. An alternative to pooled variance A researcher wants to investigate a claim that a new plant compound is effective in curbing appetite. She randomly assigns 11 rats to the treatment group and 17 rats to the control group. Rats in the treatment group are given the plant compound daily for a week, whereas rats in the control group are given a placebo. Over the course of the week, the researcher monitors the total number of calories consumed by all 28 rats. All the rats are kept separate from one another, but in their typical environments, for the duration of the week. The researcher's null hypothesis is that the rats given the plant compound consume the same number of calories as the rats given a placebo (Ho: Hplant compound Hplacebor where u is the mean number of calories consumed). Since the rats in the treatment group are independent of the rats in the control group, the researcher realizes that the design of her study uses two independent samples. The researcher knows that the number of total calories consumed by a rat over the course of a week is normally distributed. However, the researcher is not sure that the standard deviation (o) of the total calories consumed by a rat over the course of a week is the same regardless of whether the rat is given the plant compound or a placebo. uppose the mean n is 634 with a standard dev is 659 with a standard deviation of 20.5 umber of weekly calories consumed by the rats given the plant compound (the treatment group) iation of 45.0, and the mean number of calories consumed by the rats in the control group The researcher is concerned about the homogeneity of these concerns are warranted, how should the researcher proceed with variance assumption for the independent-measures t test. If an independent-measures t test? O The researcher should not use a pooled variance and should use a smaller degrees of freedom when looking up the critical t value to which to compare the t statistic. O The researcher should not use a pooled variance and should use a larger degrees of freedom when looking up O The researcher should not use a pooled variance and should use a larger degrees of freedom to calculate the t O The researcher should not use a pooled variance and should use a smaller degrees of freedom to calculate the the critical t value to which to compare the t statistic. statistic. t statistic. Assuming that the researcher's concerns are warranted, she proceeds with the independent-measures t test, making adjustments as necessary. She should use a value of differences between means s(M1 - M2). Her calculated t statistic is as her estimate of the standard error of The adjusted degrees of freedom for the researcher to use when she believes the homogenety of variance assumption has been violated isExplanation / Answer
right choice is first.
The researcher...................should use a smaller degree of freedom when looking the critical t......
(first blankd)standard error(SE)=sqrt(s12/n1+s22/n2)=sqrt(2025/11+420.25/17)=14.45
(second blank)t-statistic=(difference of mean)/SE=|(634-659)|/14.45=1.73
(third blank) degree of freedom=(s12/n1+s22/n2)2/((s12/n1)/(n1-1)+((s22/n2)/(n2-2))=12.64 ( nearese whole number=13)
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