Quizizz Exam

Which of the following summarizes and organizes data without making predictions?

• Inferential statistics

• Hypothesis testing

• Z-tests

• Descriptive statistics

Answer explanation

Descriptive statistics summarizes and organizes data, providing insights into its characteristics without making predictions. In contrast, inferential statistics and hypothesis testing involve making predictions or inferences about a population.

What type of sample gives a fair and accurate picture of the whole group because it's chosen randomly?

• Biased sample

• Convenience sample

• Purposive sample

• Unbiased sample

Answer explanation

An unbiased sample is selected randomly, ensuring that every member of the population has an equal chance of being included. This leads to a fair and accurate representation of the whole group, unlike biased, convenience, or purposive samples.

A z-score is calculated using the formula Z = (X - μ) / σ. If a score (X) is 80, the mean (μ) is 70, and the standard deviation (σ) is 5, what is the z-score?

• -2

• 0

• 1

• 2

Answer explanation

To find the z-score, use Z = (X - μ) / σ. Plugging in the values: Z = (80 - 70) / 5 = 10 / 5 = 2. Thus, the z-score is 2, which is the correct answer.

Probability is always a number between:

• -1 and 1

• 0 and infinity

• -infinity and infinity

• 0 and 1

Answer explanation

Probability values range from 0 to 1, where 0 indicates impossibility and 1 indicates certainty. Therefore, the correct answer is '0 and 1'.

What is the distribution of sample means from multiple samples called?

• Population distribution

• Sample distribution

• Data distribution

• Sampling distribution

Answer explanation

The distribution of sample means from multiple samples is called the sampling distribution. It reflects how the means vary from sample to sample, which is crucial for inferential statistics.

The formula for Standard Error of the Mean (SEM) is SEM = SD / √n. If the standard deviation (SD) is 10 and the sample size (n) is 100, what is the SEM?

• 10

• 0.1

• 100

• 1

Answer explanation

To find the SEM, use the formula SEM = SD / √n. Here, SD = 10 and n = 100. Thus, SEM = 10 / √100 = 10 / 10 = 1. Therefore, the correct answer is 1.

Which type of hypothesis predicts a specific direction of change?

• Null hypothesis

• Two-tailed hypothesis

• Non-directional hypothesis

• One-tailed hypothesis

Answer explanation

A one-tailed hypothesis predicts a specific direction of change, indicating whether a variable will increase or decrease. In contrast, a two-tailed or non-directional hypothesis does not specify the direction.

A p-value of 0.05 indicates a significance level (alpha) of:

• 0.10

• 0.01

• 0.95

• 0.05

Answer explanation

A p-value of 0.05 indicates that the significance level (alpha) is set at 0.05. This means there is a 5% risk of concluding that a difference exists when there is none, making 0.05 the correct choice.

A t-test is used to determine if:

• Data is normally distributed

• Two variables are correlated

• The standard deviation of a sample is known

• Two means are significantly different

Answer explanation

A t-test is specifically designed to compare the means of two groups to determine if they are significantly different from each other. Therefore, the correct answer is that a t-test assesses if two means are significantly different.

When is a one-sample t-test used?

• To compare two sample means

• To compare two population means

• When the population standard deviation is known

• To compare a sample mean to a population mean

Answer explanation

A one-sample t-test is used to compare a sample mean to a known population mean, helping to determine if the sample provides enough evidence to infer about the population. Thus, the correct choice is to compare a sample mean to a population mean.