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A test that measures math anxiety was given to 50 male and 50 female students. The results were as follows: $$\begin{aligned}&\text { Males: } \quad \bar{x}=70.5, s=13.2\\\&\text { Females: } \bar{x}=75.7, s=13.6\end{aligned}$$ Construct a \(95 \%\) confidence interval for the difference between the mean anxiety scores.

Short Answer

Expert verified
The confidence interval is calculated by using the given measures and applying the formulas for standard error and confidence interval. The final result will depend on the computed value of the standard error.

Step by step solution

01

Analyze Provided Data

The sample size for both male and female students is 50. For males, the sample mean is 70.5 with a standard deviation of 13.2. For females, the sample mean is 75.7 with a standard deviation of 13.6.
02

Determine Standard Error

The standard error of the difference between two independent means is given by the formula: \[SE = \sqrt{\frac{s_1^2}{n_1} + \frac{s2^2}{n_2}}\]. Substituting provided values, we get \[SE = \sqrt{\frac{13.2^2}{50} + \frac{13.6^2}{50}}\]
03

Identify Critical Value

The critical value for a 95% confidence interval from the Z-distribution is approximately 1.96 since this distribution is typically used for large sample sizes (greater than 30).
04

Compute Confidence Interval

The formula for the confidence interval is \[\bar{X}_1 - \bar{X}_2 \pm z * SE \]. Substituting known values, we get the confidence interval as \[70.5 - 75.7 \pm 1.96 * SE\]
05

Positive and Negative Interval Values

Calculate the positive and negative interval values using the above equations.
06

Interpretation

If the confidence interval obtained includes 0, we can say that there is no significant difference between the two means. Otherwise, if 0 is not in the interval, there’s significant difference between the two means.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Math Anxiety
When dealing with statistics, especially in topics related to psychology or education, terms like 'math anxiety' become particularly relevant. Math anxiety is the emotional response individuals may have to mathematics, which can affect their learning and performance. In educational studies, it's common to measure math anxiety to understand how it impacts students' achievements. In the exercise, a math anxiety test is administered to students and the results are used to compare the level of math anxiety between genders. Understanding such a psychological concept is important for educators and researchers as it sheds light on the challenges faced by students and the need for supportive measures in the curriculum.

For example, lower math anxiety could correlate with better performance, and knowing the average levels of this anxiety can inform teaching strategies or lead to the development of targeted interventions. The calculation of a confidence interval for the difference between mean anxiety scores among genders gives statistical weight to the observed differences, enabling educators to evaluate the importance and the potential impact of their interventions.
Standard Error
The standard error is a crucial statistical term that refers to the measure of the precision with which a sample statistic represents a population parameter. Simply put, it's an estimation of the uncertainty or variability of a sample mean if we were to take multiple samples from the same population. Think of it as an indication of how much the sample means you get might 'jump around' if you were to repeatedly draw samples.In the context of our math anxiety exercise, the standard error is used to assess the variability in the difference between the means of two groups (in this case, male and female students). The formula for calculating the standard error for the difference between means takes into account the standard deviations of both groups and their respective sample sizes. The smaller the standard error, the closer our sample mean is likely to lie to the true population mean – which in turn makes our confidence in the interval stronger.
Z-distribution
The Z-distribution, also known as the standard normal distribution, is symmetrical and bell-shaped, representing the theoretical distribution of standardized values called z-scores. These scores tell us how many standard deviations an observation is from the mean. The Z-distribution is a cornerstone concept in statistics and is widely used when building confidence intervals, especially when we have large sample sizes (n > 30).When calculating a 95% confidence interval, as in the math anxiety exercise, we use the Z-distribution to find a 'critical value' — the number of standard errors away from the sample mean we need to go to capture the central 95% of the data. This critical value often turns out to be 1.96 for a 95% confidence interval. Multiplying this value by the standard error gives us the margin of error, which, when added to and subtracted from the sample mean, provides the range of the confidence interval.
Standard Deviation
A close relative of the standard error is the standard deviation. It represents the spread or dispersion of a set of values in a dataset. The standard deviation tells us, on average, how far each value lies from the mean. Unlike the standard error, standard deviation is used to describe the variability within a single sample, not the variability of the sample mean.In the exercise, the standard deviation is given for the math anxiety scores of males and females. These values, along with the sample size, are plugged into a formula to calculate the standard error for the difference in means. A larger standard deviation indicates a greater spread in the anxiety scores, which could imply a diverse set of responses or experiences with math within that group. Understanding the standard deviation helps us interpret the standard error and, by extension, the confidence interval we're constructing.
Sample Mean
The sample mean, often denoted as \( \bar{X} \), is simply the arithmetic average of all the data points in a sample. It's a central concept in statistics because it's used as an estimate of the population mean, which would be the average if we could measure every single individual in the group we're interested in. The sample mean is a critical value in creating confidence intervals since it is the point estimate around which we construct the range of plausible values for the population mean.In the provided math anxiety exercise, both the male and female groups have their sample means, which are used as the starting points for constructing the confidence interval of the difference between the two groups' mean anxiety scores. Varying scores affect the confidence interval width and provide insight into the certainty of the data's representation of the whole population.

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Most popular questions from this chapter

In a survey of 300 people from city \(A, 128\) prefer New Spring soap to all other brands of deodorant soap. In city \(\mathrm{B}, 149\) of 400 people prefer New Spring soap. Find the \(98 \%\) confidence interval for the difference in the proportions of people from the two cities who prefer New Spring soap.

The guidelines to ensure the sampling distribution of \(p_{1}^{\prime}-p_{2}^{\prime}\) is normal include several conditions about the size of several values. The two binomial distributions \(B(100,0.3)\) and \(B(100,0.4)\) satisfy all of those guidelines. a. Verify that \(B(100,0.3)\) and \(B(100,0.4)\) satisfy all guidelines. b. Use a computer to randomly generate 200 samples from each of the binomial populations. Find the observed proportion for each sample and the value of the 200 differences between two proportions. c. Describe the observed sampling distribution using both graphic and numerical statistics. d. Does the empirical sampling distribution appear to have an approximately normal distribution? Explain.

A study in the New England Journal of Medicine reported that based on 987 deaths in southern California, right-handers died at an average age of 75 and left-handers died at an average age of \(66 .\) In addition, it was found that \(7.9 \%\) of the lefties died from accident-related injuries, excluding vehicles, versus \(1.5 \%\) for the right-handers; and \(5.3 \%\) of the left- handers died while driving vehicles versus \(1.4 \%\) of the right-handers. Suppose you examine 1000 randomly selected death certificates, of which 100 were left-handers and 900 were right-handers. If you found that 5 of the left- handers and 18 of the right-handers died while driving a vehicle, would you have evidence to show that the proportion of left-handers who die at the wheel is significantly higher than the proportion of right-handers who die while driving? Calculate the \(p\) -value and interpret its meaning.

A chemist is testing a proposed analytical method and has no established standards to compare it with, so she decides to use the currently accepted method for comparison. She takes a specimen of unknown concentrate and determines its concentration 12 times using the proposed method. She then takes another specimen of same unknown concentrate and determines its concentration 12 times using the current method. Do these two samples represent dependent or independent samples? Explain.

Determine the \(p\) -value for each hypothesis test for the mean difference. a. \(\quad H_{o}: \mu_{d}=0\) and \(H_{a}: \mu_{d}>0,\) with \(n=20\) and \(t \star=1.86\) b. \(\quad H_{o}: \mu_{d}=0\) and \(H_{a}: \mu_{d} \neq 0,\) with \(n=20\) and \(t \star =-1.86\) c. \(\quad H_{o}: \mu_{d}=0\) and \(H_{a}: \mu_{d}<0,\) with \(n=29\) and \(t \star =-2.63\) d. \(\quad H_{o}: \mu_{d}=0.75\) and \(H_{a}: \mu_{d}>0.75,\) with \(n=10\) and \(t \star =3.57\)

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