Question

ASSIGNMENT:

Enter the hypothetical data below in SPSS to use for the assignment.  The SPSS commands: 'file', 'new', 'data' will create a spreadsheet in which to enter the data below (manually).

Case Control Treatment

1                              5                              6

2                              4                              7

3                              5                              5             

4                              4                              6

5                              5                              5

6                              6                              6

7                              5                              5

8                              4                              6

9                              5                              5

10                           5                              10

In this experiment, all participants rated the credibility of fake news stories on a scale of 1 to 10, with higher numbers indicating greater belief. Subjects made ratings after writing a control essay about doing something successfully, and also after writing an essay about an incident in which they were bullied, rejected or otherwise socially excluded (the treatment condition).

1. In conceptual terms, the hypothesis is that social exclusion increases belief in fake news. State this hypothesis in statistical terms and include the correct notation. [1 point]

2. Explain why the t test for dependent (paired) samples is the appropriate test for the hypothesis in terms of the formula for t. [1 point]

3. Compute the means, standard deviations. [1 point]

4. Compute and interpret the effect size (d) for the differences between means. [2 points]

5. Summarize the results of the t test. Also include the correct notation. Are the results of the test significant, i.e., likely in the population? Why or why not? Should you reject or retain the null hypothesis? [4 points]

6. Summarize the results in terms of the conceptual hypothesis and variables. Explain why you think the results have practical meaning (or not). Refer to both t and d in your answer. [1 point]

Answer 1

1. In conceptual terms, the hypothesis is that social exclusion increases belief in fake news. State this hypothesis in statistical terms and include the correct notation. [1 point]

Ans:

where d=treatment-control

2. Explain why the t test for dependent (paired) samples is the appropriate test for the hypothesis in terms of the formula for t. [1 point]

Ans: The scale of control and treatment are collected from the same case. Therefore, there is a dependent between the control and treatment for each case. Hence, the t-test for dependent (paired) samples is the appropriate test for the hypothesis in terms of the formula for t.

3. Compute the means, standard deviations. [1 point]

Ans: Mean and standard deviation of the difference d=treatment - control are 1.30 and 1.70294 respectively.

4. Compute and interpret the effect size (d) for the differences between means. [2 points]

Effect size is mean divided by standard deviation=1.30/ 1.7029=0.7624. It is more than 0.5. Hence, we can conclude that is is a large effect size.

5. Summarize the results of the t test. Also include the correct notation. Are the results of the test significant, i.e., likely in the population? Why or why not? Should you reject or retain the null hypothesis? [4 points]

Paired Samples Test
		Paired Differences					t	df	Sig. (2-tailed)
		Mean	Std. Deviation	Std. Error Mean	95% Confidence Interval of the Difference
					Lower	Upper
Pair 1	Treatment - Control	1.30000	1.70294	.53852	.08179	2.51821	2.414	9	.039

Ans: The estimated p-value given at table is for two tail. But, for one right tail, it is .039/2=0.0195 and less than 0.05 level of significance. Hence, we reject the null hypothesis and conclude that social exclusion increases belief in the fake news at 005 level of significance.

6. Summarize the results in terms of the conceptual hypothesis and variables. Explain why you think the results have practical meaning (or not). Refer to both t and d in your answer. [1 point]

The estimated t-value is more than critical t-value at 0.05 level of significance. Hence, we reject the null hypothesis and conclude that social exclusion increases belief in the fake news at 005 level of significance.