1 answer

Aa Aa Tips 4. Factors that influence a hypothesis test Suppose you conduct a hypothesis test...

Question:

Aa Aa Tips 4. Factors that influence a hypothesis test Suppose you conduct a hypothesis test about a population mean when the
more. 5. Effect size - Cohens d and r squared Aa Aa An industrial/organizational psychologist has been consulting with a com
Aa Aa Tips 4. Factors that influence a hypothesis test Suppose you conduct a hypothesis test about a population mean when the standard deviation is unknown by calculating at statistic and determining whether to reject the null hypothesis. Assume that your statistic is a positive value and that you will reject the null hypothesis when t is very large. For each of the potential changes to the components of your study design or the results listed below, determine the change to the t statistic, and then select "Increases," "Decreases," or "Stays the same" from the dropdown menu in the right-hand column. Tips Unlimited The t statistic red Change in Study Design or Results A decrease in the sample variance (82) A decrease in the obtained difference (M-1) An increase in the sample size (n) A decrease in the significance level (such as using a - .01 instead of a - .05) Options re er a FREE 7.
more. 5. Effect size - Cohen's d and r squared Aa Aa An industrial/organizational psychologist has been consulting with a company that runs weekend job-seeking workshops for the unemployed. He collected data on several issues related to these workshops and, after conducting statistical tests, obtained statistically significant findings. He needs to find a way to evaluate effect size so that he can make recommendations to the company. One of the psychologist's findings is that 1 year after the workshop, a sample of 36 job seekers who received training on resume writing scored an average of 7.3 as measured on a 9-point job-search motivation scale, with a standard deviation of 1.5. The typical job seeker scores 6.1 points. The psychologist finds that the estimated Cohen's dis , the t statistic is 4.80, and r2 is Using Cohen's d and Cohen's guidelines for interpreting the effect size with the estimated Cohen's d, there is a treatment effect. Using r2 and the extension of Cohen's guidelines for interpreting the effect size using r2, there is a treatment effect. (Hint: When using Cohen's guidelines for interpreting the effect size, if the value lies between two categories, then specify the range covered by both categories, for example, medium to large.) Another one of the psychologist's findings is that a sample of 121 job seekers who received training on dressing for interviews worked an average of 6.1 hours per week, with a standard deviation of 1.2. The typical job seeker works 5.7 hours. He finds that the estimated Cohen's dis the t statistic is 3.64, and r2 is Using Cohen's d and Cohen's guidelines for interpreting the effect size with the estimated Cohen's d, there is a treatment effect. Using r2 and the extension of Cohen's guidelines for interpreting the effect size with r2, there is a treatment effect.

Answers

For the given problem,

Let \mu denote the population mean, with unknown standard deviation. We need to compare this mean to a hypothesized value \mu_{0} .

To test: H_{0}:\mu =\mu_{0} Vs say, H . HO

The appropriate statistical test to test the above hypothesis would be a One sample t test, with test statistic given by,

t=\frac{M-\mu_{0}}{s/\sqrt{n}} \sim t_{n-1}

where, M = Sample mean, s2 = Sample variation

1.Decrease in sample variance

From the test statistic, we find that the sample variance lies in the denominator of the test statistic and hence, is inversely proportional to t.Therefore,

Decrease in sample variance (s2) increases the t statistic.

2. Decrease in obtained difference

From the test statistic, we find that the difference M-\mu lies in the numerator of the test statistic and hence, is directly proportional to t.Therefore,

Decrease in obtained difference decreases the t statistic.

3. Increase in sample size n:

From the t statistic,

t=\frac{M-\mu}{\frac{s}{\sqrt{n}}}

=\frac{(M-\mu)\sqrt{n}}{s}

We find that the difference n lies in the numerator of the test statistic and hence, is directly proportional to t.Therefore,

Increase in sample size n increases the t statistic.

4.

Decrease in significance level alpha from 0.05 to 0.01.

Since, the observed / computed test statistic t has nothing to do with the significance level (it is the critical value of t that is obtained for a particular alpha, to which this observed t is compared to arrive at a decision of its significance), the t statistic remains the same.

5.

Given: n=36,M=7.3,s=1.5

Cohen's d can be computed using the formula:

d=\frac{X-M}{s}

For a student who scored 6.1,

\dpi{80} d=\frac{6.1-7.3}{1.5}=-0.8 and   t=\frac{7.3-6.1}{1.5/\sqrt{36}}=4.8

And

r^{2}=\frac{t^{2}}{t^{2}+df}

where, df for one sample t test = n - 1 = 36 - 1 = 35:

\Rightarrow r^{2}=\frac{(4.80)^{2}}{(4.80)^{2}+35}

= 0.397

Hence, using the guidelines for interpreting the effect sizes, for cohen's d:

Cohen's d Effect size
0.2 Small
0.5 Medium
0.8 Large

The cohen's d obtained (d = -0.8) shows a large treatment effect.

r Effect size
0.1 Small
0.3 Medium
0.5 Large

Here, r=\sqrt{0.397}=0.63 which suggests large effect.

Hence, using r2, we may say that there is a large effect.

For n = 121, M = 6.1, s = 1.2:

Cohen's d can be computed as:

d=\frac{X-M}{s}

=\frac{5.7-6.1}{1.2}

= -0.33

Interpreting cohen's d, we may say that there is a small to medium treatment effect.

And t = 3.64, for 121 - 1 = 120 df

r^{2}=\frac{(3.64)^{2}}{(3.64)^{2}+120}

= 0.099

Here, r=\sqrt{0.099}=0.32 which suggests a medium effect

Interpreting r2, we may say that there is a medium treatment effect.

.

Similar Solved Questions

1 answer
Show your work Count the number of operations and the big-O time complexity in the worst-case...
Show your work Count the number of operations and the big-O time complexity in the worst-case and best-case for the following code int small for ( i n t i = 0 ; i < n ; i ++) { i f ( a [ i ] < a [ 0 ] ) { small = a [ i ] ; } } Show Work Calculate the Big-O time complexity for the following cod...
1 answer
A wave on a string has an amplitude of 0.567 mm and is propagating with a...
A wave on a string has an amplitude of 0.567 mm and is propagating with a speed of 15.0 m/s in the positive x direction. If the frequency of the wave is 42.0 Hz, what is the speed of the string at x = 1.25 cm and t= 0.0625 s? (Hint: not looking for a wave speed)...
1 answer
How do you simplify # \frac { ( 4- 3i ) ( 4+ 3i ) } { 3- 4i }#?
How do you simplify # \frac { ( 4- 3i ) ( 4+ 3i ) } { 3- 4i }#?...
1 answer
Below are the ages of 20 winners of the Acadeiny Award for Best Actor and Best...
Below are the ages of 20 winners of the Acadeiny Award for Best Actor and Best Actress. Best Actor: 42 54 52 37 38 60 32 45 60 32 45 60 46 40 36 50 47 29 43 37 Best Actress: 32 4 1 33 31 74 33 32 22 49 61 21 41 26 33 44 80 42 29 33 4) Create a back to back stem and leaf plot. TABLE 2. Back to back s...
1 answer
Estimate (using right endpoints) the given integral?
Estimate (using right endpoints) the given integral #int_a^bf(x)dx# by using a Reiman Sum? #int_1^3dx/x#...
1 answer
Q) A proton's speed as it passes point A is 3.00×104 m/s . It follows the...
Q) A proton's speed as it passes point A is 3.00×104 m/s . It follows the trajectory shown in the figure. (Figure 1) What is the proton's speed at point B? Express your answer with the appropriate units. Figure 1 of 1 Br 30V 10 V -10 V...
1 answer
2. Warden Inc. uses a job-order costing system in which any underapplied or overapplied overhead is...
2. Warden Inc. uses a job-order costing system in which any underapplied or overapplied overhead is closed out to cost of goods sold at the end of the month. The company's cost of goods manufactured for March was $152,000 and its beginning and ending inventories were: Inventories: Beginning Endi...
1 answer
What is the number of oxygen atoms in #Al_2(SO_4)_3#?
What is the number of oxygen atoms in #Al_2(SO_4)_3#?...
1 answer
Question 26 Which of the following would NOT shift the labor demand curve for bakers? An...
Question 26 Which of the following would NOT shift the labor demand curve for bakers? An increase in the quantity of capital and land used in the bakery A decrease in the number of people willing to work in a bakery New technology that makes bakers more efficient A decrease in the price baked goods ...
1 answer
[-/10 Points] DETAILS SCALCET8 11.2.043. Determine whether the series is convergent or divergent by expressing sn...
[-/10 Points] DETAILS SCALCET8 11.2.043. Determine whether the series is convergent or divergent by expressing sn as a telescoping sum (as in Example 8). 00 6 2.1 n5 convergent divergent If it is convergent, find its sum. (If the quantity diverges, enter DIVERGES.)...
1 answer
What problem would attend failure to mark the position of the solvent front on the TLC...
What problem would attend failure to mark the position of the solvent front on the TLC plate immediately after developing the plate?...
1 answer
Organic hydrogenation reactions, in which H2 and an "unsaturated" organic compound combine, are used in the food, fuel,...
Organic hydrogenation reactions, in which H2 and an "unsaturated" organic compound combine, are used in the food, fuel, and polymer industries. In the simplest case, ethene (C2H4) and H2 form ethane (C2H6). If 161 kJ is given off per mole of C2H4 reacting, how much heat is released when 15.9...
1 answer
EBook The response to a question has three alternatives: A, B, and C. A sample of...
eBook The response to a question has three alternatives: A, B, and C. A sample of 120 responses provides 59 A, 22 B, and 39 C. show the frequency and relative frequency distributions (use 2 decimal for the relative frequency column). Class Frequency Relaive Frequency Total...
1 answer
For this activity, you will assume the role of a manager of flight operations for an...
For this activity, you will assume the role of a manager of flight operations for an aviation organization. Conduct research and develop your organization’s weather policy and procedures to brief to the organization’s president. Your presentation must include: Strategies to collect relia...
1 answer
How might transferring specific genes from legumes into rice plants help reduce malnutrition?
How might transferring specific genes from legumes into rice plants help reduce malnutrition?...