PSYC 1010 Unit 2 Quiz Questions

Unit 2 quiz questions 1. **What is the purpose of descriptive statistics?**\ a) To make predictions based on sample data\ b) To infer conclusions about a population from a sample\ c) To summarize, organize, and simplify data\ d) To test hypotheses using inferential procedures\...

Unit 2 quiz questions 1. **What is the purpose of descriptive statistics?**\ a) To make predictions based on sample data\ b) To infer conclusions about a population from a sample\ c) To summarize, organize, and simplify data\ d) To test hypotheses using inferential procedures\ **Correct Answer:** **c**\ **Explanation:** Descriptive statistics focus on summarizing and organizing data, while inferential statistics involve drawing conclusions beyond the data set. 2. **Which measure of central tendency is most affected by extreme scores?**\ a) Mean\ b) Median\ c) Mode\ d) Range\ **Correct Answer:** **a**\ **Explanation:** The mean takes into account every value in a dataset, so extreme values can significantly shift it. 3. **In a normal distribution, what is the relationship between the mean, median, and mode?**\ a) Mean is greater than median, which is greater than mode\ b) Mean and median are the same, but mode is different\ c) Mean = Median = Mode\ d) Mode is always the largest value\ **Correct Answer:** **c**\ **Explanation:** A perfectly normal distribution is symmetrical, so the three measures of central tendency coincide. 4. **A frequency distribution must meet which of the following conditions?**\ a) The sum of all frequencies must equal 100\ b) It must contain both discrete and continuous data\ c) Categories must be exhaustive and mutually exclusive\ d) Each category must contain an equal number of observations\ **Correct Answer:** **c**\ **Explanation:** A frequency distribution must ensure every data point fits into only one category (mutually exclusive) and that all data points are accounted for (exhaustive). 5. **What type of graph is most appropriate for nominal or ordinal data?**\ a) Histogram\ b) Bar graph\ c) Polygon\ d) Scatterplot\ **Correct Answer:** **b**\ **Explanation:** Bar graphs are best for categorical (nominal or ordinal) data because the bars do not touch, emphasizing distinct categories. 6. **What does the 75th percentile indicate?**\ a) The lowest 25% of the scores\ b) The middle score of a dataset\ c) The score at which 75% of the data falls below it\ d) The most frequently occurring score\ **Correct Answer:** **c**\ **Explanation:** Percentiles indicate relative standing within a dataset; the 75th percentile means that 75% of the scores are below it. 7. **Which of the following is NOT a measure of variability?**\ a) Standard deviation\ b) Range\ c) Interquartile range\ d) Median\ **Correct Answer:** **d**\ **Explanation:** The median is a measure of central tendency, not variability. 8. **Which measure of dispersion is most affected by extreme values?**\ a) Variance\ b) Standard deviation\ c) Range\ d) Median absolute deviation\ **Correct Answer:** **c**\ **Explanation:** The range is calculated as the difference between the highest and lowest values, so it is highly sensitive to outliers. 9. **What is the primary purpose of standard deviation?**\ a) To measure the spread of scores in a distribution\ b) To determine the most frequently occurring value\ c) To calculate the probability of an event occurring\ d) To find the middle score in a dataset\ **Correct Answer:** **a**\ **Explanation:** Standard deviation quantifies how much the scores in a dataset deviate from the mean. 10. **If all values in a dataset are the same, what will be the standard deviation?**\ a) 0\ b) 1\ c) The same as the mean\ d) Undefined\ **Correct Answer:** **a**\ **Explanation:** If all values are identical, there is no variability, so the standard deviation is 0. 11. **What does the summation symbol (Σ) represent in statistics?**\ a) Multiplication of all values\ b) The total number of observations\ c) The addition of a set of values\ d) The difference between two values\ **Correct Answer:** **c**\ **Explanation:** The summation symbol (Σ) is used to represent the sum of a series of numbers. 12. **Which of the following statements about z-scores is true?**\ a) A z-score of 0 represents the lowest value in a dataset\ b) A positive z-score means the value is below the mean\ c) Z-scores standardize data by measuring deviations from the mean\ d) Z-scores are only used in descriptive statistics\ **Correct Answer:** **c**\ **Explanation:** Z-scores measure how far a value is from the mean in standard deviation units. 13. **What proportion of data falls within one standard deviation of the mean in a normal distribution?**\ a) 50%\ b) 68%\ c) 95%\ d) 99%\ **Correct Answer:** **b**\ **Explanation:** In a normal distribution, approximately 68% of the data falls within one standard deviation of the mean. 14. **Which of the following is NOT a characteristic of a normal distribution?**\ a) It is symmetrical\ b) The mean, median, and mode are identical\ c) It has skewness\ d) It follows the empirical rule\ **Correct Answer:** **c**\ **Explanation:** A normal distribution has no skew; it is perfectly symmetrical. 15. **Which measure is best for determining the probability of a score occurring in a normal distribution?**\ a) Range\ b) Standard deviation\ c) Z-score\ d) Mode\ **Correct Answer:** **c**\ **Explanation:** The z-score allows us to determine how far a score is from the mean and thus find its probability. 16. **Which graph type is most appropriate for visualizing a frequency distribution of a continuous variable?**\ a) Bar graph\ b) Pie chart\ c) Histogram\ d) Boxplot\ **Correct Answer:** **c**\ **Explanation:** Histograms are used for continuous data, where bars touch to represent the continuity of the variable. 17. **Why is the median sometimes preferred over the mean?**\ a) It considers all values in the dataset\ b) It is less affected by extreme values\ c) It is easier to calculate\ d) It is always more accurate\ **Correct Answer:** **b**\ **Explanation:** The median is robust to outliers and skewed distributions, making it a better measure in such cases. 18. **What is a key feature of cumulative frequency distributions?**\ a) They show only the most common score\ b) They indicate the number of scores at or below a given value\ c) They represent data using bars\ d) They are only used for nominal data\ **Correct Answer:** **b**\ **Explanation:** Cumulative frequency distributions sum up frequencies up to a given score. 19. **If a dataset has a large standard deviation, what does this indicate?**\ a) The values are close together\ b) There is little variability\ c) The values are spread out\ d) The dataset is skewed\ **Correct Answer:** **c**\ **Explanation:** A large standard deviation indicates greater spread among values. 20. **What does a percentile rank of 90 mean?**\ a) The score is the highest in the dataset\ b) 90% of the data falls below this score\ c) The score is 90 standard deviations from the mean\ d) The data follows a normal distribution\ **Correct Answer:** **b**\ **Explanation:** A percentile rank of 90 means that 90% of the observations are lower than that score. 21. **What is the difference between simple frequency and relative frequency distributions?**\ a) Simple frequency is the number of times a score appears; relative frequency is its proportion in the dataset.\ b) Relative frequency is always higher than simple frequency.\ c) Simple frequency is a percentage, while relative frequency is not.\ d) Relative frequency only applies to nominal data.\ **Correct Answer:** **a**\ **Explanation:** Simple frequency counts occurrences, while relative frequency expresses them as proportions or percentages. 22. **What should be considered when creating class intervals for a grouped frequency table?**\ a) The number of categories must match the number of data points.\ b) The class intervals should be of equal width and mutually exclusive.\ c) Each class interval must contain at least five data points.\ d) Class intervals must be uneven to reflect natural groupings.\ **Correct Answer:** **b**\ **Explanation:** Grouped frequency distributions require **equal width** and must ensure **mutually exclusive categories**. 23. **When should you use a frequency polygon instead of a histogram?**\ a) When the dataset is small and has categorical variables\ b) When you have interval or ratio data with a large number of values\ c) When you are comparing nominal data\ d) When the bars in the histogram overlap\ **Correct Answer:** **b**\ **Explanation:** **Frequency polygons** are best for **continuous data** when there are **many data points**. 24. **If a student's exam score falls in the 85th percentile, what does this mean?**\ a) They scored higher than 85% of the students.\ b) They scored lower than 85% of the students.\ c) Their score was exactly at the mean.\ d) Their score was the most frequently occurring score.\ **Correct Answer:** **a**\ **Explanation:** **Percentile rank** shows the **percentage of scores below a given value**. 25. **Which of the following is an example of an ordinal scale?**\ a) Temperature in Celsius\ b) Ranking students as first, second, or third place in a competition\ c) The number of students in a class\ d) Blood pressure in mmHg\ **Correct Answer:** **b**\ **Explanation:** **Ordinal data** represents a ranking **without equal intervals**. 26. **A distribution where most scores cluster to the left and the tail extends to the right is called?**\ a) Positively skewed\ b) Negatively skewed\ c) Normal distribution\ d) Bimodal distribution\ **Correct Answer:** **a**\ **Explanation:** **Positively skewed distributions** have a long **right** tail. 27. **What does kurtosis measure in a dataset?**\ a) The presence of skewness\ b) The peak and flatness of a distribution\ c) The number of outliers\ d) The difference between the mean and median\ **Correct Answer:** **b**\ **Explanation:** Kurtosis describes **whether a distribution is more peaked or flat**. 28. **Which measure of central tendency is least affected by extreme scores?**\ a) Mean\ b) Median\ c) Mode\ d) Range\ **Correct Answer:** **b**\ **Explanation:** **The median** is resistant to outliers and skewed distributions. 29. **Why is standard deviation preferred over range as a measure of variability?**\ a) Standard deviation accounts for all data points, while range only considers two values.\ b) Range is always larger than standard deviation.\ c) Standard deviation cannot be calculated if the data contains outliers.\ d) The range changes depending on the number of data points.\ **Correct Answer:** **a**\ **Explanation:** **Standard deviation uses all data points**, making it **more reliable** than range. 30. **How does an outlier affect the mean and standard deviation of a dataset?**\ a) The mean shifts, and the standard deviation increases.\ b) The mean stays the same, and the standard deviation decreases.\ c) The mean becomes negative, and the standard deviation disappears.\ d) Outliers do not affect statistical measures.\ **Correct Answer:** **a**\ **Explanation:** **Outliers pull the mean** toward them and **increase variability**. 31\. **Which of the following is true for a negatively skewed distribution?**\ a) The mean is greater than the median, which is greater than the mode.\ b) The mean is less than the median, which is less than the mode.\ c) The mean, median, and mode are equal.\ d) The distribution has no tail.\ **Correct Answer:** **b**\ **Explanation:** In a **negatively skewed** distribution, the **mean is pulled to the left**, making it **lower than the median and mode**. 32\. **Which measure of central tendency is the best representation of data in a highly skewed distribution?**\ a) Mean\ b) Median\ c) Mode\ d) Range\ **Correct Answer:** **b**\ **Explanation:** The **median** is best for skewed data because it is **not affected by extreme values**. 33. **A researcher is analyzing the annual incomes of people in a city. She notices that most of the incomes are low, but a few very wealthy individuals significantly increase the overall mean. What type of distribution is this?**\ a) Normal\ b) Positively skewed\ c) Negatively skewed\ d) Uniform\ **Correct Answer:** **b**\ **Explanation:** A **positively skewed** distribution occurs when **a few high values pull the mean upward**, which is common in income data. 34. **A company wants to determine the most popular shoe size among its customers. Which measure of central tendency should they use?**\ a) Mean\ b) Median\ c) Mode\ d) Standard deviation\ **Correct Answer:** **c**\ **Explanation:** **Mode** is the most appropriate measure when determining the **most frequently occurring** category in a dataset. 35. **A teacher recorded the test scores of her students and found that the mean was much lower than the median. What does this suggest about the distribution of test scores?**\ a) It is symmetric.\ b) It is positively skewed.\ c) It is negatively skewed.\ d) It follows a normal curve.\ **Correct Answer:** **c**\ **Explanation:** If the **mean is lower than the median**, the distribution is **negatively skewed**, indicating **low outliers**. 36. **A hospital administrator is analyzing patient wait times in the emergency department. Most patients wait less than an hour, but a few have waited 5-6 hours. What type of distribution does this likely create?**\ a) Normal\ b) Positively skewed\ c) Negatively skewed\ d) Bimodal\ **Correct Answer:** **b**\ **Explanation:** The **long right tail** caused by a few **very long wait times** creates a **positively skewed** distribution. 37. **A dataset includes the heights of 500 students. If one student is 7 feet tall, how will this affect the measures of central tendency?**\ a) The mean will increase, but the median will stay the same.\ b) The median will increase significantly.\ c) The mode will shift to a higher value.\ d) The standard deviation will decrease.\ **Correct Answer:** **a**\ **Explanation:** A single extreme **outlier** affects the **mean**, but not the **median**, since the median is based on position. 38. **A real estate agent is trying to describe the housing market in a city. Most homes are valued between \$200,000 and \$400,000, but a few luxury homes are valued at \$2 million or more. What is the best way to describe the central tendency of home prices?**\ a) Report the mean price.\ b) Report the median price.\ c) Report the range of home prices.\ d) Use a histogram only.\ **Correct Answer:** **b**\ **Explanation:** **The median is preferred** because **outliers (luxury homes) can inflate the mean**, making it misleading. 39. **A survey is conducted on the number of hours people watch TV per week. The results show that most people watch between 0-10 hours, but a small group watches 40+ hours per week. Which measure would best represent the \"typical\" number of hours watched?**\ a) Mean\ b) Median\ c) Mode\ d) Range\ **Correct Answer:** **b**\ **Explanation:** The **median is resistant to extreme values**, so it provides a better measure than the mean in a skewed dataset. 40. **Which of the following is the best measure of central tendency for the following dataset?**\ **Data:** 3, 5, 7, 8, 9, 10, 50\ a) Mean\ b) Median\ c) Mode\ d) Standard deviation\ **Correct Answer:** **b**\ **Explanation:** The **median (8) is better** than the **mean (which is inflated by the outlier 50)**.