question archive At what age do babies learn to crawl? Does it take longer to learn in the winter when babies are often bundled in clothes that restrict their movement? Data were collected from parents who brought their babies into the University of Denver Infant Study Center to participate in one of a number of experiments between 1988 and 1991
At what age do babies learn to crawl? Does it take longer to learn in the winter when babies are often bundled in clothes that restrict their movement? Data were collected from parents who brought their babies into the University of Denver Infant Study Center to participate in one of a number of experiments between 1988 and 1991
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At what age do babies learn to crawl? Does it take longer to learn in the winter when babies are often bundled in clothes that restrict their movement? Data were collected from parents who brought their babies into the University of Denver Infant Study Center to participate in one of a number of experiments between 1988 and 1991. Parents reported the birth month and the age at which their child was first able to creep or crawl a distance of 4 feet within 1 minute. The resulting data were grouped by month of birth: January, May, and September:
Crawling age
Birth month
Mean
St. dev.
n
January
29.84
7.08
32
May
28.58
8.07
27
September
33.83
6.93
38
Crawling age is given in weeks. Assume the data represent three independent simple random samples, one from each of the three populations consisting of babies born in that particular month, and that the populations of crawling ages have Normal distributions.
A partial ANOVA table is given below.
Source
Sum of squares
DF
Mean square
F
Groups
505.26
Error
53.45
Total
Use data to answer A-E must show calculations for all please.
A) What is the value of the ANOVA F statistic for testing the equality of the population means?
Is it A) 4.73 B) 9.45 C) 3.15 or D) 6.30
B) The null hypothesis for the ANOVA F test is that the population mean crawling ages are equal for all three birth months. What is the alternative hypothesis?
a)
The three population mean crawling ages are all different from each other.
b)
Not all three population mean crawling ages are equal to each other.
c)
The population mean crawling age is larger for January than the other 2 months.
d)
The population mean crawling age is larger for May than the other 2 months.
C) Determine whether each of the following statements is true or false.
A)
This is a randomized, designed experiment.
B)
The data show no strong evidence of violating the assumption that the three populations have the same standard deviation.
C)
An ANOVA cannot be used on these data because the sample sizes are different.
D)
An ANOVA cannot be used on these data because the data show very strong evidence of non-Normal population distributions.
D) What are the degrees of freedom for the groups term? A) 94 B)3 C) 96 D)2
E) What are the degrees of freedom for the error term? A) 94 B) 2 C) 96 D) 3
