Chapter 10

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Chapter10

3.Whatdoes αstandfor, and what two things does it determine?

Theα stands for the alpha level, sometimes called the significancelevel. It helps determine the possibility of making the wrongdecision in the instance that the null hypothesis is true.

6.(a)What does H0communicate?

H0communicates hypothesis in support to the experimental parameterbeing tested

(b)What does Hacommunicate?

H0communicates the alternative hypothesis to the parameter beingtested.

9.(a)What is power?

Poweris the odds that the effect will be observed as it happens

(b)Why do researchers want to maximizepower?

Itwill helps by increasing the chances of accepting the truehypothesis.

(c)What result makes us worry whether we have sufficient power?

Whenit is not clear whether the null or the alternative hypothesis shouldbe accepted or rejected.

(d)Why is a one-tailed test more powerful than a two-tailed test?

Aone-tailed test that uses an alpha level of 5% often provides alarger area of rejection of the null hypothesis this helps minimizethe chances of making the type II error that would occur as a resultof the two-tailed test with a smaller area of 2.5% or less.

13.Describethe experimental hypotheses and the independent and dependentvariables when we study:

(a)whether the amount of pizza consumed by college students duringfinals week increases relative to the rest of the semester,

H0:µ of pizza consumed by college students during finals week &gt µof pizza consumed during the rest of the semester

Ha:µ of pizza consumed by college students during finals week &lt µof pizza consumed during the rest of the semester

Theindependent variable is the periods of the semester

Thedependent variables include the amount of pizza consumed and theappetites of the students

(b)whetherbreathing exercises alter blood pressure

H0:µ for taking breathing exercises &lt µ for blood pressure

Ha:µ for taking breathing exercises ≥ µ for blood pressure

Thedependent variable is the µ for blood pressure

Theindependent variable is the µ for taking breathing exercises

(c)whethersensitivity to pain is affected by increased hormone levels, and

H0:µ for sensitivity to pain ≥ µ for hormone levels

Ha:µ for sensitivity to pain ≥ µ for hormone levels

Thesensitivity to pain is the independent variable while the hormonelevels are the dependent variables.

(d)whether frequency of daydreaming decreases as a function of morelight in the room.

H0:µ for daydreaming ≥ µ for light in the room

Ha:µ for daydreaming ≠ µ for light in the room

Theamount of light in the room is the independent variable while thefrequency of daydreaming is the dependent variable.

24.Weask if the attitudes toward fuel costs of 100 owners of hybridelectric cars (Ẋ=76) aredifferent from those on a national survey of owners of non-hybridcars (µ =65, ὸX=24) .Higher scores indicate a more positive attitude.

(a)Isthis a one or two-tailed test?

Thisis a two-tailed test

(b)In words, what are H0andHa?

H0:There is no difference between fuel costs of 100 owners hybridelectric cars from those on national survey of owners of non-hybridcars.

Ha:Thereis difference between fuel costs of 100 owners hybrid electric carsfrom those on national survey of owners of non-hybrid cars.

Chapter11

3.(a)Whatis the difference between Sandợ?

Sxmeasures the sample standard deviation while σx is the populationstandard deviation, meaning all the data were used to calculate it.

(b)Howis their use the same?

Theyboth describe a particular type of standard deviation

11.Weask whether a new version of our textbook is beneficial ordetrimental to students learning statistics. On a national statisticsexam, µ=68.5 forstudents using other textbooks. A sample of students using this bookhas the following scores:

6469 92 77 71 99 82 74 69 88

1. What are H0 and Ha for this study?

H0:µ= 68.5

Ha:µ68.5

1. Compute tobt.

 X X2 64 4096 69 4761 92 8464 77 5929 71 5041 99 9801 82 6724 74 5476 69 4761 88 7744 ∑X=785 ∑X2=62797

Substitutingfrom the table,

Substitutingwith the results of the equation above,

Substitutingwith values,

1. With α= .05, what is tcrit?

Degreesof freedom = 10 – 1 = 9

Fromthe t-table tcrit(= .05, df = 9) = ±2.26

1. What do you conclude about the use of this book?

Becausethe tobt falls in the rejection region, we would rejectthe null. Therefore the newversion of our textbook is beneficial to students learningstatistics.

12.Aresearcher predicts that smoking cigarettes decreases a person’ssense of smell. On a test of olfactory sensitivity, the _fornonsmokers is 18.4. A sample of people who smoke a pack a dayproduces these scores:

1614 19 17 16 18 17 15 18 19 12 14

1. What are H0 and Ha for this study?

Ho: Smokingcigarete decreases a person’s sense of smell

Ha:Smoking cigarette does not decrease a persons sense of smell

1. Compute tobt.

 X X2 16 256 14 196 19 361 17 289 16 256 18 324 17 289 15 225 18 324 19 361 12 144 14 196 N=12 ∑X=195 ∑X2=3221

Substitutingfrom the table,

Substitutingwith the results of the equation above,

Substitutingwith values,

1. With α = .05, what is tcrit?

Fromthe t-table tcrit(= .05, df = 11) = ±2.20

Becausethe tobt falls in the rejection region, the researcher would rejectthe null.The researcher should therefore conclude that smoking cigarette doesnot decrease a person’s sense of smell.

1. Compute the confidence interval for µ

13.Foofystudies if hearing an argument in favor of an issue altersparticipants’ attitudes toward the issue one way or the other. Shepresents a 30-second argument to 8 people. In a national survey aboutthis issue, µ=50.She obtains Ẋ=53.25and s2X=569.86.

(a)What are H0andHa?

Ho:µ=50

H1:µ 50

(b)What is tobt?

Substitutingwith values,

(c)With α= .05,whit is tcrit?

Fromthe t-table tcrit(= .05, df = 7) = ±2.37