Question 1

A curve that is flat relative to the normal curve is described as ______.

Accepted Answer

A platykurtic curve has a flatter curve relative to the normal curve, indicating a lower peak and less variability in the data.

Question 2

For a sampling distribution (the distribution of the sample results), the standard deviation is referred to as the ______.

Accepted Answer

For a sampling distribution, the standard deviation is referred to as the standard error. This is because it represents the variability or error between the sample means and the population mean. Options A, B, and D are not correct terms for the standard deviation of a sampling distribution.

Question 3

A data plot showing a positive skew has ______.

Accepted Answer

A positive skew means that the majority of the data is clustered around the lower values, with a few very high values that "skew" the overall distribution towards the right. This results in the "tail" of the plot being in the high numbers.

Question 4

When data are skewed, which of the following statistics are NOT necessary to adequately describe the data?

Accepted Answer

The answer of When data are skewed, which of the...

Question 5

For a t test comparing two groups that consist of different individuals, we use the t test for ______ samples.

Accepted Answer

The t test for independent samples is appropriate when comparing two groups that consist of different individuals, as they are not dependent on each other. The dependent samples t test (also known as the paired samples t test) is used when the two groups are related or matched (e.g. pre-test and post-test scores of the same individuals). "Asymmetric" and "symmetric" are not terms used to describe types of t tests.

Question 6

A curve that is steep or high relative to the normal curve is described as ______.

Accepted Answer

A curve that is steep or high relative to the normal curve is described as leptokurtic.

Question 7

The formula for standard deviation for a set of scores includes ______.

Accepted Answer

Standard deviation formula requires the calculation of the deviation score for each individual score, thus making choice C the correct answer. The formula does not involve the population (choice A), median (choice B), or mode (choice D).

Question 8

For a t test comparing two groups that consist of the same individuals, we use the t test for ______ samples.

Accepted Answer

When comparing two groups that consist of the same individuals, we use the dependent samples t-test, also known as the paired samples t-test or the repeated measures t-test. This is because the data in each group is not independent, as the same individuals are being compared before and after an intervention or under different conditions. The t-test for independent samples is used when the two groups being compared are completely separate and unrelated. The options C and D are not relevant to the type of t-test used in this scenario.

Question 9

The probability of sampling any value under the normal curve that is less than the mean is ______.

Accepted Answer

The probability of sampling any value under the normal curve that is less than the mean is 0.50 (50%) because the normal distribution is symmetric around the mean.

Question 10

The probability of sampling any value under the normal curve that is greater than the mean is ______.

Accepted Answer

The mean of a normal distribution is at the center of the curve, which divides the area into two equal halves. Therefore, the probability of sampling any value greater than the mean is 50%.

Question 11

In a normal distribution, most values are ______.

Accepted Answer

In a normal distribution, the majority of values are concentrated around the mean value and become less frequent as one moves away from the mean towards the extremes of the distribution. This is why it is called a "normal" distribution, as it represents a typical or average distribution of data. Therefore, most values are in the middle of the distribution.

Question 12

Inferential statistics tell us that as long as we are prepared to accept a known level of uncertainty in our projections, ______.

Accepted Answer

Inferential statistics rely on probability and estimation to make projections about a larger population based on a smaller sample. As such, there is always a level of uncertainty associated with these projections, which is typically expressed through confidence intervals or p-values. However, by setting a predetermined level of uncertainty (e.g., a 95% confidence interval), we can use inferential statistics to make reasonably accurate projections even with smaller sample sizes. Therefore, choice A is the best answer.

Question 13

A range of values calculated from a sample is called the ______.

Accepted Answer

A range of values calculated from a sample is called a confidence interval. Confidence metric, error interval, and confidence level are related concepts but do not accurately describe a range of values calculated from a sample.

Question 14

A data plot showing a negative skew has ______.

Accepted Answer

A negative skew means that the majority of the data falls on the higher end of the scale, while a smaller number of outliers fall on the lower end. This creates a "tail" in the low numbers, which is exactly what choice A describes.

Question 15

A tri-modal profile means that a distribution of data plots out showing _______ peak(s).

Accepted Answer

A tri-modal profile indicates that the distribution of data has three peaks.

Question 16

The z distribution allows us to calculate ______.

Accepted Answer

The z distribution is used to calculate the probability that a sample has captured the characteristics of the population from which it was drawn, also known as the standard normal distribution. It allows us to determine the likelihood of obtaining a particular sample mean or sample proportion given the population mean and standard deviation.

Question 17

The probability of sampling any value under the normal curve is ______.

Accepted Answer

The probability of sampling any value under the normal curve is 1.00, because the normal curve is a continuous probability distribution that covers all possible values.

Question 18

What does the t test compare?

Accepted Answer

The t test compares the mean scores of two groups on the same variable to determine the probability that the groups are different. This is commonly used in hypothesis testing to determine if there is a significant difference between two groups.

Question 19

Nonparametric statistics should be used when we ______.

Accepted Answer

Nonparametric statistics are used when we cannot assume a normal distribution in the data. They do not depend on specific distribution assumptions but rather on the ranking or ordering of the data. Nonparametric methods can be used for both continuous and categorical variables, and do not require knowledge of the sample size.

Question 20

Conceptually, the t test is based on ______.

Accepted Answer

The t test is based on the differences in means for a variable common to two groups. It assesses whether these differences are statistically significant and unlikely to have occurred by chance.

Quiz 8: Generalizing From Research Results: Inferential Statistics