Measures of Central and Variability Tendency Custom essay

While researchers typically show frequency distributions in a table as a way to organize large amounts of data, you may have also seen frequency distributions displayed graphically, using histograms or smooth curves. Consider the bell curve, or normal distribution, and remember the first time you saw one. What can the frequency of occurrence tell us about a characteristic or phenomenon? Can it tell you how much better or worse you performed on a test when compared to the scores of your classmates? Imagine that you collected those test scores and created a frequency distribution. There might be, for example, many scores clustered around the 90% mark and no scores in the 0% to 60% range. Refer to the following graphic for more information. If your frequency histogram only included the range of observed scores (60% to 100%) instead of the entire range of possible scores (0% to 100%), it might appear that you had a normal distribution when really there was a negative skew. What other factors can you consider when planning how to interpret data?

Frequency distributions, particularly the normal curve, are an ongoing concept in this class. The normal distribution is very common in behavioral research. When you describe data with many different scores, you will understand more about them if you know the resulting distribution type. For example, if you notice a test score frequency distribution in the shape of two equal humps, or in a bimodal distribution, you can say with some certainty that scores fell into two ranges showing two discrete groupings of students’ scores. This Assignment focuses on your ability to understand and distinguish among the different types of frequency distributions, measures of central tendency, and measures of variability and understand what they mean in relation to a sample.

To prepare for this Assignment, review mean, median, and mode as well as the different types of distributions in your textbook.


Recall that for this week’s Discussion you considered data related to opening or attracting a new restaurant. Now consider that you ask 20 participants to estimate how many times a month they go out to dinner and you receive these responses:

1, 2, 5, 8, 2, 4, 8, 4, 2, 3, 6, 8, 7, 5, 8, 4, 0, 7, 6, and 18.


To complete this Assignment submit calculations of the following measures of central tendency and variability using the data set provided. Include an explanation of how you calculated each measure and what information each measure gives you about the dining behavior of the sample.

Finally, create a data file in SPSS and run analyses to find the mean and standard deviation. Note: Your hand-calculated mean and standard deviation will differ somewhat from the calculations in SPSS due to rounding.

Hand-calculated mean:

SPSS mean:




Deviation of the highest score from the mean:

Hand-calculated standard deviation (Please also state the hand-calculated values for ∑X2and(∑X)2.):

SPSS standard deviation:

Explain how the standard deviation (SD) and the deviation of a single score differ in the information they provide. Explain how each measure (mean, median, mode, deviation of the highest score from the mean, and standard deviation) would change if the score of 18 was eliminated from the data set.

Explain the type of distribution (positive skew, negative skew, bimodal distribution, or normal distribution) your data create. Explain how you know the type of distribution and what the data tells you about your sample.

Probability Testing Custom essay

You almost certainly engage in decision making every day. Usually, you choose an option because you believe that it will have a more pleasing outcome than the other choice(s). If you knew your likelihood of succeeding or failing, you would have an even easier time making a decision. Each decision you make is influenced by probability.

As you would expect, psychologists like to keep the probability of coming to false conclusions in research as low as possible, though you know that it is almost impossible to make a decision that is entirely free of error. But what are the implications of making different types of errors? Are all errors equally dangerous, or do some have more critical importance than others? Consider the four possible decisions a jury could reach in a murder trial when the sentence is the death penalty. If the jury’s verdict is correct, either an innocent defendant goes free or a guilty defendant is convicted. However, what about when the jury makes an error, and a guilty defendant goes free or an innocent man is convicted? How do we calculate the probability of each of these types of errors?

Probability tests might help you make decisions of low importance, such as purchasing goods, but they can also play a role in making critically important decisions. For example, scientists often use probability to evaluate the safety of drugs for human use. This Discussion presents an exercise in probability in the context of a research study for a new drug to treat depression.

To prepare for this Discussion, review the textbook sections on probability and Type I and Type II errors.


Imagine that a pharmaceutical company is testing a new medication to treat major depression in people whose symptoms have not been helped by existing medications.You are part of a panel of professionals who must decide if the drug should be considered safe for human trials. The null hypothesis is that the drug is considered to be safe. The alternative hypothesis is that the drug is considered to be unsafe. In the above scenario, would a Type I or Type II error be worse? Why? Be sure to spell out what a Type I and Type II error would be in this example so your explanation is clear.

Address the following as you prepare for your posting:

  • Consider an example of when it is acceptable to have a pof .05 versus .01. What effect would this have on your interpretation of the drug’s safety?
  • Consider the likelihood of making a Type I or Type II error. What effect could these errors have on your interpretation of the drug’s safety?
  • Draft a recommendation regarding whether the drug should be seen as safe for human trials.
  • Consider how the scenario would need to change in order to have a different recommendation.

Post  your recommendation on whether human testing trials should begin on the drug described in the scenario. Explain why or why not. Specifically, include how the use of different p values (.05 versus .01) and concerns related to Type I and II errors would influence your recommendation. What conditions would need to change for your recommendation to change? Justify your post using the Learning Resources and current literature.

Making Inferences from a Sample custom essay

Hypothesis Testing:

Hypothesis testing is the foundation of conducting research in psychology. Researchers must first determine the question they wish to answer and then state their prediction in terms of null and alternative hypotheses. Once the hypotheses are stated, researchers move on to data collection. However, once the results come in, the real challenge is to determine if they have meaning, if the results are significant.

For example, a researcher asks whether attending a private secondary school leads to higher or lower performance on a test of social skills when compared to students attending publicly funded schools. After stating the hypotheses and collecting data, the researcher sees that the mean social skills scores for the two schools are different, but is the difference meaningful or just due to random variation? There must be a significant difference in order to say that the two schools really do have students with different social skills.


Imagine that the drug for severe depression from this week’s Discussion was approved for use in humans. Researchers now want to know whether people using this drug have a different life expectancy than the rest of the general population. A sample of 100 patients who use the drug are followed over time. Those that use the drug have a mean life expectancy of 71.30 years. The mean life expectancy for the general population is 75.62 years. The population standard deviation is 28.


To complete this Assignment, responses to the following:

  • Identify the independent and dependent variables.
  • Explain whether the researcher should use a one-tailed or a two-tailed ztest and why.
  • State the null hypothesis in words (not formulas).
  • State the alternative hypothesis in words (not formulas).
  • Calculate the obtained zscore by hand and state the critical value with an alpha of .05. Provide your calculations in your Assignment submission.
  • Would you retain or reject the null hypothesis? Why?
  • Explain whether the results are significant, and why or why not.
  • What should the researcher conclude about the life expectancy of the sample in comparison to the population?
  • In general, explain the relationship between zscores and the standard deviation.


Using t Tests Custom essay

In order to set up a research study, you must state your expectations and hypothesize what will happen if you compare your participants to those in the general population or to those in another group. You also need to determine the type of relationship you expect. In comparing means of groups, you may predict that one group’s mean will be higher than another. You may predict that one group’s mean will be lower than another. In either of these cases, you will implement a one-tailed test because you are predicting the direction of the relationship. If you think the means will be different but you are not sure if they will be higher or lower, you implement a two-tailed test. Once you plan your study and state your hypotheses, you collect your data, calculate results, and interpret the meaning of those results.

In this Discussion, you will create a scenario that would require using the one-sample t test and then explain what you would change in order to turn the one-sample t test into a two-sample t test. While you will not need to complete calculations, you will be asked to explain your study design and discuss why you made the choices you did. This experience will help you later to review studies and critique the interpretation of data.

Post your one-sample t test scenario. What would need to change in the scenario to result in the need for a two-sample t test? Explain whether the two-sample scenario would be categorized as having independent samples or related samples and discuss why. Support your post using the Learning Resources

Computing t Tests Custom essay

The one-sample t test discussed in Chapter 6 requires that you know the population mean. It is unusual to have this information, so most studies compare two samples instead. Each sample measures a different condition of the independent variable.

Before conducting a study, it is important to know if you would need to conduct a matched-samples t test or an independent-samples t test. Independent samples consist of two groups of different people. One group has been randomly selected and is not specifically tied to who is in the other group. Matched samples are groups that are deliberately selected to be similar to each other (matched pairs) or they are the same people in both groups (repeated measures). For example, you might want to select two groups that have similar heights. If height could affect the experiment, it could be best to match the groups on that variable. This Assignment will allow you to convey your understanding of the basic concepts related to t testing and will allow you to practice setting up and conducting an inferential parametric test in SPSS.


Imagine you are a researcher who believes that a relaxation technique involving visualization will help people with mild insomnia fall asleep faster. You randomly select a sample of 20 participants from a population of mild insomnia patients and randomly assign 10 to receive visualization therapy. The other 10 participants receive no treatment.

You then measure how long (in minutes) it takes participants to fall asleep. Your data are below. The numbers represent the number of minutes each participant took to fall asleep.

No Treatment (X1) Treatment (X2)
22 19
18 17
27 24
20 21
23 27
26 21
27 23
22 18
24 19
22 22


To complete this Assignment, submit by Day 7 a response to each of the following:

  • Explain whether you chose to use an independent-samplestest or a matched-samples t test. Provide a rationale for your choice.
  • Identify the independent and dependent variables.
  • Knowing you believe the treatment will reduce the amount of time to fall asleep, state the null and alternate hypotheses in words (not formulas).
  • Explain whether you would use a one-tailed or two-tailed test and why.
  • Explain whether you have homogeneity of variance, and explain how you know. Explain why it is important to know if you have homogeneity of variance.
  • Identify the obtained tvalue for this data set using SPSS.
  • Identify the degrees of freedom and explain how you determined it.
  • Identify the pvalue.
  • Explain whether you should retain or reject the null hypothesis and why.
  • Explain what you can conclude about the effectiveness of visualization therapy

Classical Music; Early Abolitionist Art and Literature Custom essay

using sources under the Explore heading as the basis of your response:

Listen to one (1) composition (for a symphony) by Haydn or Mozart, either at the Websites below or in this week’s Music Folder. Identify the work that you have chosen, and describe the way in which the composition expresses the specific qualities of the Classical music style. Use the key terms from the textbook that are related to that particular music style, and explain what you like or admire about the work. Compare it to a specific modern musical work for which you might use the term “classic” or “classical”.

Explain whether you think an autobiographical or fictional account by a slave (such as Phillis Wheatley and Olaudah Equiano) is more persuasive than a biographical or fictional account by a white author (such as John Gabriel Stedman or Aphra Behn). Explain whether you believe the representations of slavery in the visual arts (such as William Blake’s illustrations, William Hackwood’s cameo, or John Singleton Copley’s painting) were more compelling and convincing of the injustices of slavery than the literary representations already mentioned. In your explanations, use specific examples and consider both audience and the content and nature of the work. Identify the literary or art form in modern times that you think is most effective at depicting injustice.


Classical Music

Chapter 25 (pp. 826-832), classical style described; examples; review the Week 3 “Music Folder”
Haydn at and
Mozart at and

Early Abolitionist Art & Literature

Chapter 26 (pp. 870-2): Equiano, Stedman, Wheatley, Behn; Chapter 26 (pp. 877-879): Equiano and Behn
Wheatley at
Chapter 26 (pp. 870-873): Blake, Hackwood, Copley

Timeline of Gendered Movements Custom essay


If there is one important lesson you can learn as social scientists it is this: historical events never appear in isolation, but instead, are connected to previous events. In this Assignment you will develop a 6-point timeline that shows how the counterculture movements and issues of equality were intertwined to define the 1960s. Give the timeline a descriptive title. Use footnotes or endnotes to fully describe the reason for including each item

The differing approaches of nursing leaders and managers to issues in practice Custom essay

Write a 1,000-1,250-word essay describing the differing approaches of nursing leaders and managers to issues in practice. To complete this assignment, do the following:

  1. Select an issue from the following list: nursing shortage and nurse turn-over, nurse staffing ratios, unit closures and restructuring, use of contract employees (i.e., registry and travel nurses), continuous quality improvement and patient satisfaction, and magnet designation.
  2. Compare and contrast how you would expect nursing leaders and managers to approach your selected issue. Support your rationale by using the theories, principles, skills, and roles of the leader versus manager described in your readings.
  3. Identify the approach that best fits your personal and professional philosophy of nursing and explain why the approach is suited to your personal leadership style.
  4. Use at least two references