Suppose that your team has been analyzing data from an impact evaluation that used a posttest-only control group design. There were 227 participants in the treatment group, and 236 in the control group. The key outcome is a scale score measuring COVID vaccine hesitancy. In the dataset, the experimental group variable is named TREAT, and takes the value 0 for control group members and 1 for treatment group members; while the outcome variable is named VAXHES. A member of your team used SPSS to conduct a two-sample t-test, and you have been presented with the output appearing below. How would you quantify the estimated effect of the intervention in terms of a mean difference, and does the statistical test provide support for the effectiveness of the intervention?

Group Statistics

	TREAT Experimental Group	N	Mean	Std. Deviation	Std. Error Mean
VAXHES Vaccine	.00	236	3.3465	.38006	.02523
Hesitancy Scale	1.00	227	3.2459	.36907	.02402

Independent Samples Test

		Levene's Test for Equality of Variances	t-test for Equality of Means
									95% Confidence Interval of the Difference
		F	Sig.	t	df	Sig. (2-tailed)	Mean Difference	Std. Error Difference	Lower	Upper
VAXHES Vaccine Hesitancy	Equal variances assumed	.025	.873	2.888	461	.004	.10055	.03482	.03123	.16897
Scale	Equal variances not assumed			2.886	458.860	.004	.10055	.03484	.03209	.16901