Use z test for difference of means. Show work please 4. Baby walkers are seats hanging from frames that allow babies to sit upright with their legs dangling and feettouching the floor. Walkers have wheels on their legs that allow the infant to propel the walker around the houselong before he or she can walk or even crawl. Typically, babies use walkers between the ages of 4 months and11 months.Because most walkers have tray tables in front that block babies' views of their feet, child psychologists havebegun to question whether walkers affect infants' cognitive development. One study compared mental skills ofa random sample of those who used walkers with a random sample of those who never used walkers. Mentalskill scores averaged 113 for 54 babies who used walkers (standard deviation of 12) and 123 for 55 babies whodid not use walkers (standard deviation of 15).(a) Is there evidence that the mean mental skill score of babies who use walkers is different from the meanmental skill score of babies who do not use walkers? Explain your answer.(b) Suppose that a study using this design found a statistically significant result. Would it be reasonable toconclude that using a walker causes a change in mean mental skill score? Explain your answer.

Introduction: Denote μ1, μ2 as the true mean mental skill score of individuals who used baby…

Answered: 4. Baby walkers are seats hanging from…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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Use z test for difference of means. Show work please

4. Baby walkers are seats hanging from frames that allow babies to sit upright with their legs dangling and feet
touching the floor. Walkers have wheels on their legs that allow the infant to propel the walker around the house
long before he or she can walk or even crawl. Typically, babies use walkers between the ages of 4 months and
11 months.
Because most walkers have tray tables in front that block babies' views of their feet, child psychologists have
begun to question whether walkers affect infants' cognitive development. One study compared mental skills of
a random sample of those who used walkers with a random sample of those who never used walkers. Mental
skill scores averaged 113 for 54 babies who used walkers (standard deviation of 12) and 123 for 55 babies who
did not use walkers (standard deviation of 15).
(a) Is there evidence that the mean mental skill score of babies who use walkers is different from the mean
mental skill score of babies who do not use walkers? Explain your answer.
(b) Suppose that a study using this design found a statistically significant result. Would it be reasonable to
conclude that using a walker causes a change in mean mental skill score? Explain your answer.

Definition Definition Measure of central tendency that is the average of a given data set. The mean value is evaluated as the quotient of the sum of all observations by the sample size. The mean, in contrast to a median, is affected by extreme values. Very large or very small values can distract the mean from the center of the data. Arithmetic mean: The most common type of mean is the arithmetic mean. It is evaluated using the formula: μ = 1 N ∑ i = 1 N x i Other types of means are the geometric mean, logarithmic mean, and harmonic mean. Geometric mean: The nth root of the product of n observations from a data set is defined as the geometric mean of the set: G = x 1 x 2 ... x n n Logarithmic mean: The difference of the natural logarithms of the two numbers, divided by the difference between the numbers is the logarithmic mean of the two numbers. The logarithmic mean is used particularly in heat transfer and mass transfer. ln x 2 − ln x 1 x 2 − x 1 Harmonic mean: The inverse of the arithmetic mean of the inverses of all the numbers in a data set is the harmonic mean of the data. 1 1 x 1 + 1 x 2 + ...

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