PSYC FPX 4700 Assessment 2 Central Tendency and Probability
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PSYC FPX 4700 Assessment 2 Central Tendency and Probability

PSYC FPX 4700 Assessment 2 Central Tendency and Probability


Capella University

PSYC FPX 4700 Statistics for the Behavioral Sciences

Prof. Name


Central Tendency and Probability

Problem Set 2.1: Characteristics of the Mean

To study perception, a researcher selects a sample of participants (n = 12) and asks them to hold pairs of objects differing in weight, but not in size, one in each hand. The researcher asks participants to report when they notice a difference in the weight of the two objects. Below is a list of the difference in weight (in pounds) when participants first noticed a difference. Answer the following questions based on the data given in the table.

Difference in Weight


State the following values for this set of data:

  • Mean ___
  • Median ___
  • Mode(s) ___

What is the shape of this distribution? Hint: Use the values of the mean, median, and mode to infer the shape of this distribution. __

Problem Set 2.2.a: Interpret Means in a Chart

General life satisfaction across culture. Gilman and colleagues (2008) measured general life satisfaction in 1,338 adolescents from two individualistic nations (Ireland, United States) and two collectivist nations (China, South Korea) using the Multidimensional Students’ Life Satisfaction Scale (MSLSS). Mean participant scores on the MSLSS are given in the following table.

PSYC FPX 4700 Assessment 2 Central Tendency and Probability





United States 4.39 4.61
Ireland 4.37 4.64
China 4.41 4.56
South Korea 3.92 3.78

Among which group was general life satisfaction lowest on average? __

Among which group was general life satisfaction highest on average? __

Problem Set 2.2.b: Understanding Standard Deviations in a Chart

Acceptable height preferences. Salska and colleagues (2008) studied height preferences among dating partners. In their first study, they reviewed Yahoo! Personals for heterosexual individuals living within 250 miles of Los Angeles, California, and recorded the acceptable range of heights for their dating partners. The following table lists some of the results.




Shortest acceptable height, inches 68.9 60.6
Tallest acceptable height, inches 75.3 69.8

Overall, did men or women show greater variability in their responses? Explain.

Problem Set 2.3: Range, Variance, and Standard Deviation in Excel

A sample of likes per post on Facebook: 45, 789, 16, 5, 486, 1, 87, 18, 48, 1

Problem Set 2.4: Range, Variance, and Standard Deviation in JASP

Use dataset likes.jasp. This dataset is a sample of likes per post on Facebook.

Answer: Does your mean equal the mean calculated in Problem Set 2.3? __

Problem Set 2.5: Probability and Conditional Probability

Researchers are often interested in the likelihood of sampling outcomes. They may ask questions about the likelihood that a person with a particular characteristic will be selected to participate in a study. In this exercise, we will select a sample of one participant from the following hypothetical student population of new and returning students living on or off campus. The population is summarized in the following table.

Problem Set 2.6: Determining Probability

Probability of first marriage among women. A National Center for Health Statistics (NCHS) brief report by the Centers for Disease Control and Prevention (CDC) in 2009 identified that about 6% of women in the United States married for the first time by their 18th birthday, 50% married by their 25th birthday, and 74% married by their 30th birthday.

Based on these data, what is the probability that in a family with two daughters, the first and second daughter will be married by each of the following ages?

  • 18 years of age:___
  • 25 years of age:___
  • 30 years of age:___

Problem Set 2.7: Understanding Normal Distribution

Judging the humorousness of “lawyer” jokes. Stillman et al. (2007) conducted a study where participants listened to a variety of jokes. To determine how funny the jokes were, the researchers asked a group of 86 undergraduates to rate the jokes on a scale from 1 (very unfunny) to 21 (very funny). Participants rated a “lawyer joke” as one of the funniest jokes, with a rating of 14.48 ± 4.38 (M ± SD).

Assuming that these data are normally distributed,

What was the rating that marks the cutoff for the top 10% of participant ratings for this joke? ___

How many of the 86 undergraduates gave the joke a rating of at least 10? ___

Problem Set 2.8: Calculating z Scores in JASP

Use the dataset ratings.jasp. This dataset is a record of how a sample of senior citizens rated the Internet on a 1–10 scale, with 1 being “really distrust it” and 10 being “completely trust it”:

Answer: Which number of ratings is closest to the z score of 0?


Gilman, R., & et al. (2008). Multidimensional Students’ Life Satisfaction Scale. [Data file]. Retrieved from [URL]

Salska, I., & et al. (2008). Height preferences among dating partners. [Data file]. Retrieved from [URL]

Stillman, T., & et al. (2007). Judging the humorousness of “lawyer” jokes. [Data file]. Retrieved from [URL]

PSYC FPX 4700 Assessment 2 Central Tendency and Probability

Centers for Disease Control and Prevention. (2009). National Center for Health Statistics Brief Report. [Data file]. Retrieved from [URL]