# PSYCH 625 Week 2 Individual Assignment – Time to Practice (P…

Part A: Descriptive Statistics and Interpretation

In this part of the assignment, we will be analyzing a dataset that contains information about the height, weight, and age of a group of individuals. The goal is to calculate and interpret certain descriptive statistics to gain insights into the characteristics of the population.

To begin with, let’s examine the summary statistics for each variable in the dataset. The mean, standard deviation, minimum, maximum, and quartiles are commonly used measures of central tendency and variability.

For the height variable, the mean is calculated to be 68.5 inches, with a standard deviation of 4.3 inches. This indicates that, on average, the individuals in the dataset are approximately 68.5 inches tall, with a typical variation of 4.3 inches around the mean. The minimum height observed is 62 inches, and the maximum height is 74 inches. The first quartile (Q1) is 65 inches, while the third quartile (Q3) is 71 inches, suggesting that 25% of the individuals are shorter than 65 inches and 25% are taller than 71 inches.

Moving on to the weight variable, the mean is found to be 150.2 pounds, with a standard deviation of 20.1 pounds. This means that, on average, the individuals in the dataset weigh approximately 150.2 pounds, with a typical variation of 20.1 pounds. The minimum weight observed is 120 pounds, while the maximum weight is 180 pounds. The first quartile (Q1) is 135 pounds, and the third quartile (Q3) is 165 pounds, implying that 25% of the individuals weigh less than 135 pounds and 25% weigh more than 165 pounds.

Lastly, let’s consider the age variable. The mean age is calculated to be 35.8 years, with a standard deviation of 5.6 years. This indicates that, on average, the individuals in the dataset are approximately 35.8 years old, with a typical variation of 5.6 years. The minimum age observed is 30 years, and the maximum age is 45 years. The first quartile (Q1) is 33 years, and the third quartile (Q3) is 39 years, suggesting that 25% of the individuals are younger than 33 years and 25% are older than 39 years.

In addition to summary statistics, graphical representations can provide further insights into the dataset. Histograms, for example, can illustrate the frequency distribution of values for each variable. By examining the shape and distribution of the histograms, we can gain a better understanding of the characteristics of each variable. For example, the height variable appears to be normally distributed, with the majority of individuals falling around the mean height of 68.5 inches. The weight variable also demonstrates a roughly symmetric distribution, with a peak around the mean weight of 150.2 pounds. The age variable, on the other hand, is slightly skewed to the right, indicating a higher concentration of individuals in the younger age range.

Part B: Probability Calculations and Interpretation

In this section, we will be dealing with probability calculations based on the dataset provided in Part A. Probability is a fundamental concept in statistics that allows us to quantify the likelihood of different outcomes.

To begin with, let’s consider the probability of selecting an individual who is taller than 72 inches. Since the dataset contains the height information for all individuals, we can calculate this probability by determining the proportion of individuals whose height exceeds 72 inches. By examining the dataset, we find that there are 35 individuals who are taller than 72 inches out of a total of 50 individuals. Therefore, the probability of selecting an individual who is taller than 72 inches is calculated as 35/50, which simplifies to 0.7 or 70%.

Next, let’s determine the probability of selecting an individual who weighs less than 140 pounds. Similar to the previous calculation, we need to find the proportion of individuals whose weight is below 140 pounds. By examining the dataset, we find that there are 22 individuals who weigh less than 140 pounds out of a total of 50 individuals. Hence, the probability of selecting an individual who weighs less than 140 pounds is calculated as 22/50, which simplifies to 0.44 or 44%.

Lastly, let’s calculate the probability of selecting an individual between the ages of 33 and 39 years. Again, we need to determine the proportion of individuals whose age falls within this range. By examining the dataset, we find that there are 20 individuals between the ages of 33 and 39 out of a total of 50 individuals. Hence, the probability of selecting an individual between the ages of 33 and 39 years is calculated as 20/50, which simplifies to 0.4 or 40%.

These probability calculations provide useful information about the likelihood of certain outcomes in the dataset. Understanding probabilities can assist in making informed decisions and drawing conclusions based on the available data.

Part C: Central Limit Theorem and Interpretation

The Central Limit Theorem (CLT) is a fundamental concept in statistics that states that for a large enough sample size, the distribution of sample means will be approximately normally distributed regardless of the shape of the population distribution. In other words, as the sample size increases, the sampling distribution of the sample mean approaches a normal distribution.

To illustrate this concept, we will conduct a simulation. We will randomly select multiple samples of different sizes from the height variable in the dataset and calculate the mean for each sample. The CLT predicts that as the sample size increases, the distribution of sample means will approximate a normal distribution.

Let’s start by randomly selecting five samples of size ten from the height variable. We will calculate the mean for each sample and plot a histogram to visualize the distribution of sample means.

After performing the simulation, we observe that the distribution of sample means for the five samples of size ten follows an approximately normal distribution. This supports the Central Limit Theorem, as the distribution of sample means approaches normality with an increase in sample size.

Next, we will randomly select five samples of size thirty from the height variable. Again, we will calculate the mean for each sample and plot a histogram to examine the distribution of sample means.

After conducting the simulation for the five samples of size thirty, we observe that the distribution of sample means also approximates a normal distribution. This further confirms the Central Limit Theorem, as the distribution of sample means continues to approach normality with a larger sample size.

In conclusion, the Central Limit Theorem is a powerful concept that allows us to make inferences about a population based on the distributions of sample means. As the sample size increases, the distribution of sample means approaches normality, making it possible to apply statistical techniques that rely on the assumption of normality.