Psychology Chapter 4 Exercises

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Questions and Answers

What does the interval width represent in a grouped frequency distribution?

The specific frequency of a score within the dataset

The total number of scores in the data set

The numerical difference between the highest and lowest scores

The range of values contained in each interval (correct)

What is the term for extreme scores that fall significantly outside the range of most scores in the data set?

Outlier (correct)

Median

Interval

Anomaly

How is the real range of a data set defined?

The difference between the mean and median

One more than the difference between the largest and smallest values (correct)

The average of the largest and smallest values

The total number of intervals in the distribution

What is the purpose of a sector in a pie chart?

To represent relative percentage of a class or category Signup and view all the answers

What does the percentile rank indicate in a data distribution?

The percentage of scores below a specified score Signup and view all the answers

What is the definition of a frequency distribution?

A summary display for how often a category or score occurs. Signup and view all the answers

How is relative frequency calculated?

Frequency in each interval divided by the total number of frequencies. Signup and view all the answers

What type of graph is used to summarize the frequency of discrete and categorical data?

Bar chart Signup and view all the answers

In a relative percent distribution, what does it summarize?

The percentage of scores occurring in each interval. Signup and view all the answers

What does a frequency polygon represent?

The frequency of continuous data at the midpoint of each interval. Signup and view all the answers

What distinguishes grouped data from ungrouped data?

Grouped data is represented in intervals, whereas ungrouped data is not. Signup and view all the answers

What do the upper and lower boundaries represent in a grouped frequency distribution?

The smallest and largest values in a given interval. Signup and view all the answers

Which of the following is a characteristic of a pie chart?

It summarizes data into sectors based on relative percentages. Signup and view all the answers

What is the first step a researcher must take to code for groups in SPSS?

Click on the values column in the variable view tab. Signup and view all the answers

Which statement accurately describes a characteristic of an interval scale of measurement?

Values are assumed to be equidistant. Signup and view all the answers

Which of the following is NOT a method for entering data into SPSS?

Entering data by grouping. Signup and view all the answers

What do parameters describe in research?

Characteristics in a population. Signup and view all the answers

Which of the following statements about discrete variables is accurate?

They can only be measured in whole units. Signup and view all the answers

What is the purpose of a cumulative frequency distribution?

To distribute the sum of frequencies across intervals. Signup and view all the answers

Which of the following best describes the necessary requirements for conducting a study using the experimental method?

Randomisation, manipulation, and comparison. Signup and view all the answers

What does a cumulative relative distribution display?

The sum of relative frequencies across intervals. Signup and view all the answers

What is the definition of a multimodal distribution?

A distribution in which more than two scores occur most frequently. Signup and view all the answers

What do we call the average of a set of scores obtained by adding them up and dividing by the total number of scores?

Arithmetic Mean Signup and view all the answers

In a positively skewed distribution, where are the majority of the scores located?

Towards the left tail. Signup and view all the answers

Which type of mean should be computed if a psychologist analyzes a portion of a larger group of scores?

Sample mean Signup and view all the answers

What is the mode of the list of scores: 3, 3, 6, 6, 6, 7, 8, 8?

6 Signup and view all the answers

What type of distribution is represented by the scores: 1, 1, 2, 2, 3, 3, 4, 5, 5, 5, 6?

Bimodal Signup and view all the answers

If a psychologist records scores: 2, 2, 2, 2, 3, 8, what can we infer about the distribution?

It is positively skewed. Signup and view all the answers

What is the overall mean of the scores: 5, 3, 8, 2, 9, 7, 4, and 5?

5.37 Signup and view all the answers

What does standard deviation measure in a data set?

The average distance scores deviate from their mean Signup and view all the answers

How is population standard deviation calculated?

By calculating the square root of the population variance Signup and view all the answers

What does the interquartile range (IQR) represent?

The middle 50% of a data set Signup and view all the answers

Which measure of variability is also known as the half range of the IQR?

Semi-Interquartile Range (SIQR) Signup and view all the answers

What does Chebyshev’s theorem provide information about?

The distribution of data within standard deviations from the mean Signup and view all the answers

A biased estimator is characterized by which of the following?

It does not equal the population parameter on average Signup and view all the answers

Degrees of freedom (df) for sample variance is calculated as which of the following?

Sample size minus one (n-1) Signup and view all the answers

What is the primary purpose of calculating the sum of squares (SS)?

To find the variance of the data Signup and view all the answers

What does the empirical rule state about normally distributed data?

At least 95% of data lie within two standard deviations Signup and view all the answers

What does the range of a data set indicate?

The difference between the largest and smallest scores Signup and view all the answers

Study Notes

Chapter 4 Exercises

There is a table containing data about the number of bar presses by rats in response to food
The psychologist is interested in the number of bar presses by a group of rats (N = 8) to receive food
The sample data contains 8 observations
This is a sample, not a population
Sample data points are: 5, 3, 8, 2, 9, 7, 4, and 5

Population, Sample & Variability

The sample mean should be calculated as the psychologist is studying a sample of rats
The average number of bar presses is 5.37
The mode of the scores 5, 5, 5, 3, 6, 6, 6, 6, 6, 6, 6, 8, 8, 8, 8, 9, 9, 2, 2, 5, 5, 2, 2, 7, 8, 7, 7, 7, 7, 7, 3, 3, 5, 5, 5, 5, 7, 7, 3, 3, 3, 3, 3, 6, 6, 6, 6, 7, 8, 8, 8, 8 is 6
This distribution of scores can be classified as multimodal because more than two scores occur most often or frequently
The psychologist’s measurements represent a sample of the wider population of rats that could be studied.
The score of her 12 students are 45, 41, 47, 41, 43, 41, 40, 42, 48, 39, 47, and 48.
Calculations for the population variance include division by n, while calculations for the sample variance involve division by n-1.
The population standard deviation (σ) is a measure of variability for the average distance that scores in a population deviate from their mean
The sample standard deviation (s or SD) is a measure of variability for the average distance that scores in a sample deviate from their mean.
The interquartile range (IQR) is the range of values between the upper (Q3) and lower (Q1) quartiles of a data set.
The semi-interquartile range (SIQR) is a measure of half the distance between the upper quartile (Q3) and lower quartile (Q1) of a data set, computed by dividing the IQR in half.
The range is the difference between the largest (L) and the smallest (S) value in a data set
Quartiles divide data evenly into four equal parts
Variability is a measure of the dispersion or spread of scores in a distribution
It ranges from 0 to + ∞
Empirical Rule states that for data that are normally distributed, at least 99.7% of data lie within 3 SD of the mean, at least 95% of data lie within 2 SD of the mean, and at least 68% of data lie within 1 SD of the mean
Degrees of freedom (df) for a T distribution are equal to the degrees of freedom for sample variance for a given sample: n-1.
Each distribution is associated with specified degrees of freedom
As sample size increases, the degrees of freedom also increase
Degrees of freedom (df) for Sample Variance is the number of scores in a sample that are free to vary.
All scores except one are free to vary in a sample: n-1.
Deviation is the difference of each score from its mean and is denoted (X- µ) for a population and (x-M) for a sample.
A biased estimator is any sample statistic obtained from a randomly selected sample that does not equal the value of its respective population parameter, such as a population mean, on average.
Conversely, an unbiased estimator is any sample statistic obtained from a randomly selected sample that equals the value of its respective population parameter on average.

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Description

This quiz focuses on Chapter 4 of Psychology, exploring sample data from a study of rat behavior in response to food. It involves calculating the mean and mode and analyzing the data's variability along with understanding the concepts of population and sample. Students will work with specific data points and classifications to deepen their understanding of these statistical measures.