Statistical Method in Psychology
Query 1
1)
In order to find out if the app was indeed able to change the eating choices of the participants and what is the exact way those choices alter as the result of using the app by participants, it is necessary to compare the results on choices through different time series. To track the dynamics of choice, pairwise comparisons between the results of subjects’ performances at the beginning of first month, at the end of the first month and at the end of the second month should be done. The comparison between the performances in different periods is to be done by using the statistical tool of paired t test. The differences between the performance levels at various time periods are evaluated in terms of differences in mean values throughout the measurements. So, in order to make judgments about app’s efficiency, it is necessary that the mean values of performance are significantly different through the time. Ideally, the means of performance levels should gradually increase, reaching their peak at the end of the second month. Paired t test was chosen as the method of analysis, because it allows comparing means of the same sample in different trials. The null hypothesis is formulated as: there is no significant difference in mean values between in different time points. The alternative hypothesis is formulated as: there are significant differences in mean values between in different time points.
2)
The findings show that the app is able to produce the changes in eating choices of the participants who had been using it for two months straight. Even though effect is moderate (the observed increase in mean is 3 by the end of second month), it is proven to be consistent. It can be said that the effect is cumulative, meaning that achieving notable results will require more time, because the main increase in means is only observable in a period from the end of first month to the end of second. Through the period between the beginning and the end of the first month no serious changes in eating choices had place. To find out if the app is effective after the two-month period, more procedures of similar testing are needed.
3)
Paired Samples Test
Paired Differences
t
df
Sig. (2-tailed)
95% Confidence Interval of the Difference
Mean
Std. Deviation
Std. Error Mean
Lower
Upper
Pair 1
Choices0 - Choices1
-,19617
5,48189
,57153
-1,33144
,93909
-,343
91
,732
Pair 2
Choices1 - Choices2
-2,93974
7,63597
,79610
-4,52110
-1,35838
-3,693
91
,000
Pair 3
Choices0 - Choices2
-3,13591
7,07164
,73727
-4,60041
-1,67142
-4,253
91
,000
The conclusion on the overall moderate efficacy of the app was made on the …
