Charles Darwin, author of On the Origin of Species (1859), designed an experiment to compare the effects of cross-fertilization and self fertilization on the size of plants. He planted pairs of very similar seedling plants, one self-fertilized and one cross-fertilized, in each of pot15at the same time. After a period of time, Darwin measured the heights (in inches) of all the plants. Here are the data:

(a) Explain why it is not appropriate to perform a paired t test in this setting.

(b) A hasty student generates the Minitab output shown below. What conclusion should he draw at the α=0.05significance level? Explain

Short Answer

Expert verified

(a)Both variables are taken as independent variable. Thus, to test the comparison, will utilize independent t-test.

(b)There is no sufficient evidence to infer that there is any difference among cross and self.

Step by step solution

01

part (a) Step 1: Given information

Given in the question that, Charles Darwin, author of On the Origin of Species (1859), designed an experiment to compare the effects of cross-fertilization and self fertilization on the size of plants. He planted pairs of very similar seedling plants, one self-fertilized and one cross-fertilized, in each of 15 pots at the same time. After a period of time, Darwin measured the heights (in inches) of all the plants. Here are the data

02

Part (a) Step 2: Explanation

It is given that the designed experiment is going to comparison between the effects of cross-fertilization and self-fertilization on the size of plants.

As per the given data set, there are two variables cross and self.

Since, a paired t-test is valuable for dependent variable (or both experiments has been done on similar land or same items).

Since, both variables are taken as independent variable. Thus, to test the comparison, will utilize independent t-test.

03

Part (b) Step 1: Given information

Charles Darwin, author of On the Origin of Species (1859), designed an experiment to compare the effects of cross-fertilization and self-fertilization on the size of plants. He planted pairs of very similar seedling plants, one self-fertilized and one cross-fertilized, in each of pots at the same time. After a period of time, Darwin measured the heights (in inches) of all the plants. Here are the data

04

Part (b) Step 2: Explanation

As per the given table,

The null and alternative hypotheses are:

H0:μ=0

H1:μ0

Variable



N
Mean
St Dev
SE Mean
T
P


Diff

15
2.61
4.71
1.22
2.14
0.050

When the p-value does not equal the level of significance, the null hypothesis is rejected. The p-value (0.050) isn't quite at the 0.050 threshold of significance. The null hypothesis is not refuted in this way. As a result, there is insufficient evidence to conclude that there is a distinction between cross and self.

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Most popular questions from this chapter

Bottles of a popular cola are supposed to contain 300milliliters (ml) of cola. There is some variation from bottle to bottle because the filling machinery is not perfectly precise. From experience, the distribution of the contents is approximately Normal. An inspector measures the contents of six randomly selected bottles from a single day’s production. The results are 299.4297.7301.0298.9300.2297.0Do these data provide convincing evidence that the mean amount of cola in all the bottles filled that day differs from the target value of 300ml? Carry out an appropriate test to support your answer

The z statistic for a test of H0 :p = 0.4 versus Ha : p > 0.4 is z = 2.43. This test is

(a) not significant at either α=0.05or α=0.01.

(b) significant at α=0.05but not at α=0.01

(c) significant at α=0.01but not at α=0.05.

(d) significant at both α=0.05and α=0.01.

(e) inconclusive because we don’t know the value of ˆp .

(a) State hypotheses for a significance test to determine whether first responders are arriving within 8 minutes of the call more often. Be sure to define the parameter of interest.

(b) Describe a Type I error and a Type II error in this setting and explain the consequences of each.

(c) Which is more serious in this setting: a Type I error or a Type II error? Justify your answer.

(d) If you sustain a life-threatening injury due to a vehicle accident, you want to receive medical treatment as quickly as possible. Which of the two significance tests—H0:μ=6.7versusHa:μ<6.7 or the one from part (a) of this exercise—would you be

more interested in? Justify your answer.

In planning a study of the birth weights of babies whose mothers did not see a doctor

before delivery, a researcher states the hypotheses as

H0:x¯=1000gramsHa:x¯<1000grams

For the study of Jordanian children in Exercise 4, the sample mean hemoglobin level was 11.3 g/dl and the sample standard deviation was 1.6 g/dl. A significance test yields a P-value of 0.0016.

(a) Interpret the P-value in context.

(b) What conclusion would you make if α= 0.05? α= 0.01? Justify your answer.

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