PSYC 510

HOMEWORK: DATA ORGANIZATION AND DESCRIPTIVE STATISTICS

ASSIGNMENT INSTRUCTIONS

OVERVIEW

This Homework: Data Organization & Descriptive Statistics Assignment is designed to

assess your understanding of the concepts and applications covered thus far in this course. In this

module, you have looked at how to organize data and describe it in terms of central tendency,

dispersion, and shape of distribution. You also have covered cover how to standardize a

distribution of data in order to see how a single score compares to other scores. These topics are

covered conceptually as well as how to calculate them by hand and in SPSS. These concepts and

applications are fundamental to understanding and evaluating data as a consumer in a data-laden

world, a consumer of data within our field, and producer of research in our field.

INSTRUCTIONS

Be sure you have reviewed this module’s Learn section before completing this Homework:

Data Organization & Descriptive Statistics Assignment. This Homework: Data

Organization & Descriptive Statistics Assignment is worth 60 points. Each question is worth 3

points each. Six points are awarded for mechanics/structure.

Part I contains general concepts from this module’s Learn section.

Part II requires use of SPSS. You will have to take screen shots and/or copy and paste from

your SPSS to place answers within this file. Make sure you only insert relevant and legible

images.

Part III is the cumulative section. These may include short answer and/or use of SPSS but

will review material from previous module(s).

Directions for each subsection are provided in the top of each table (in the blue shaded

areas).

Answers should be placed where indicated (wherever there is “ANSWER”).

Submit the file as a WORD document (.doc or .docx). Make sure the filename of your

submission includes your full name, course and section.

o Example: HW4_JohnDoe_510B01

Make sure to check the Homework Grading Rubric before starting this Homework: Data

Organization & Descriptive Statistics Assignment.

Part I: General Concepts

These questions are based on the concepts covered in this

module’s assigned readings and presentations.

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1. The following data represents 18 emotional intelligence test scores. Organize these

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PSYC 510

data into a class interval frequency distribution using 3 intervals with frequency (f) and

relative frequency (rf) columns.

ANSWER: Fill in the yellow cells:

2. What is the class width?

What is the upper class limit of the first

interval?

Class width is 13

Upper class limit of first clas is 44

Answer the following question related to your assigned readings and presentations.

3. What do the following symbols

represent?

a. N

b. µ

a. Number of Scores in a distribution

b. Population mean

Use the following five (5) numbers to calculate the following by hand (must show all work

and do NOT round)

3 3 4 5 9

4. Calculate all measures of

central tendency. Label each

one.

ANSWER Mean= (3+3+4+5+9)/ 5 =

4.8

Median= 4(Mid number)

Mode= 3

5. Is this data best described as

normal, positively skewed, or

negatively skewed? How does

It cannot be a normal distributuion

because the mean, median and mode are

not

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Class Intervals (use

whole numbers)

f rf (round to

2 decimals)

31-44 3 0.17

45-58 9 0.50

59-72 6 0.33

N = 18

PSYC 510

your previous answer confirm

this?

equal.

6. Calculate the range and

average deviation. Show all

work.

Range= (9-3)=6

Average deviation= |(3-4.8) +(3-4.8)+ (4-4.8)+(5-4.8)

(9-4.8)|= 8.8 /5=average deviation of 1.76

7. Calculate the standard

deviation using the formula

from ch.5 . Show all work.

ANSWER (3-4.8)2 +(3-4.8)2+ (4-4.8)2+(5-4.8)2 +(9-

4.8)2= 21.884

Square root of 21.884 is 4.678

4.678/ 5-1= 1.1695

1.1695

8. State two ways the standard

deviation differs from the

average deviation.

1)Instead of using absolute vales of the

deviations to get rid of the negative, in

standard

deviations they are squared.

2)Standard deviation is

used in many other statistical procedures

where

average deviation is not.

Students in the psychology department consume an average of 5 cups of coffee per day with a standard

deviation of 1.75 cups. The number of cups of coffee consumed is normally distributed. Make sure

you do NOT round when answering any of these questions. When applicable, show ALL work

for full points.

9. Nancy drank 6 cups of coffee. What proportion of students

drank FEWER cups of coffee than Nancy? (do not round and

use the table in the appendix of the Jackson e-book)

ANSWER

Z =

(6-5)/1.75=0.571

4

Proportion of students

that drank fewer

=0.71567

10. Which of the following curves (A, B, or C) best illustrate

where Nancy’ s data would be?

Curve A as nancy

mean is 5 and she

drinks 6 cups

11. How many cups of coffee would an individual at the 80

th

Pr(Z<0.842)=0.8

5+0.842×1.75

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PSYC 510

percentile rank drink? (do NOT round) =6.473 cups of coffee

12. Imagine this course is over and instead of seeing your total

points earned, you are given a z score and the grade is curved

to fit a normal distribution. What would you want your z

score to be and why? (make sure you use a numerical value

and indicate whether it is positive or negative)

ANSWER

I would want a Z score

of 3 and above as they

are extreme right end

and would give me a

larger area and thus

higher percentile

Part II: SPSS Application

These questions require the use of SPSS. Remember you must

submit all of your work within this word document. You will need

to take a screen shot of your data view if necessary, or copy and

paste your output into the spaces below.

The following dataset contains scores for depression, a subscale on the DASS-21 from 18

individuals. This variable is considered scale and is discrete. Enter the following data into SPSS to

answer the following questions. Make sure you name the variable “Depression” and that you set the

scale of measurement within SPSS.

11 13 15 17 18 22

7 8 18 17 13 11

9 16 18 12 13 15

13. Insert the descriptive statistics table (NOT the frequency table) from your SPSS output.

ANSWER

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PSYC 510

14. Create a histogram of the data using SPSS and paste it below.

ANSWER

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PSYC 510

Part III: Cumulative

These questions can be related to anything covered thus far in the

course.

As part of his dissertation, Joe wanted to know if an icecream reward can increase the number

of books read by children in the first grade. The small school has four 1

st

grade classes – two

are given the reward and two are not; total number of books read at the end of the term are

compared.

15. What is the independent variable? Is it a

true manipulated variable or a subject /

participant variable?

ANSWER

The independent variable is

the reward given. It is a

manipulated variable .

16. What is the dependent variable? What is

its scale of measurement?

ANSWER

Dependent variable is the

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PSYC 510

number of books read at the end

of

the term. Scale of measurement

is Ordinal

17. He found a huge difference – students

read more in the classes rewarded with

icecream. What is a potential

confounding variable?

ANSWER

Confounding variable can be number of

students

Answer the final question related to your previous readings and presentations on reliability and

validity.

18. When you log in to take your psychology exam, you are flabbergasted to find that all of the

questions are on calculus and not psychology. The next day in class, students complain so

much that the professor agrees to give you all a makeup exam the following day. When

you arrive in class the next day, you find that although the questions are different, they are

once again on calculus. In this example, there should be high reliability of what type?

What type(s) of validity is the test lacking? Explain your answers.

ANSWER

This should be high Alternate-forms reliability because the test is given twice to

the same people, however the test is changed for the second test and is different but

it was the same topic as the earlier. This test lacks content validity as the content was in calculus

instead of psychology. It also lacks Face validity as when students looked at the test they

understood its not a psychology test .

Submit this assignment by 11:59 p.m. (ET) on Sunday of Module 4. Remember to name the file

appropriately.

Done!

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