Teaching the subject of Power Supply Network at college level towards developing the ability to detect and solve practical problems - 28

- Create a frequency table f i (%) (% of students with score X i ), select the output output address cell, type the command: = cell address containing score frequency Xi×l00/N, for example =G19×100/33 click and drag to the remaining cells: in which G19 is the address cell containing score frequency Xi, N= 33 total number of students.

- Make a progressive convergence frequency table f a (% of students with score X i or higher): select the location cell

corresponding to point 1 in TN and DC class, enter: 100; in the address box corresponding to point 2, enter the command: = address of the cell corresponding to point 1 just entered 100 - address of point 1 cell in the frequency table. Use the mouse to drag and drop until all the point address boxes are filled.

- Draw a frequency distribution characteristic chart, draw a progressive convergence frequency curve. Select the frequency result block or the progressive convergence frequency of the class TN class.

DC (start cell address: end cell address of the frequency table or progressive convergence frequency table). Click on the Chat Wizard icon on the toolbar to select the required chart type, then click Next and finally click Finish.

3) Processing data of centripetal tendency measurements, calculating parameters

Statistical feature numbers using Excel:

- Calculate the values ​​of mean, median, mode, standard deviation, variance, kurtosis, skewness (coefficient of asymmetry compared to normal distribution), range, maximum value, minimum value, sum, number of samples (count), and 95% confidence interval of the mean.

Select menu: Tools/Data Analysis…/Descriptive Statistics

Enter the following items:

+ Input Range: absolute address containing data

+ Output Range: output address

+ Confidence Level for Mean

Results of calculation of statistical characteristic parameters

Table 1. Description of results and corresponding functions in Excel

- When the number of calculated samples N ≥ 30; calculate the average score (Mean): is the average value of the scores to determine the level of achievement of the students' tests; use z-Test (z-Test two Samples for Means).

Select menu: Tools/Data Analysis…/z-test:Two Sample for Means

Data entry and processing:

+ Variable 1 Range , Variable 2 Range: absolute address of data area

+ Variable 1 Variance(known), Variable 2 Variance(known): respective variances of experimental class and control class

+ Labels: select when there is a variable name at the top of the column or row

+ Alpha: significance level (usually 0.05)

+ Output options: choose how to output results

z-Test: Two Sample for Means

Table 2. Description of hypothesis testing results

- Use the U criterion to test the hypothesis H 0 (μ1 = μ2) about the equality of two overall means, the experimental and control classes, with N ≥30 and the overall variance known by replacing the two sample variances (Sample Variance) of the experimental and control classes.

If │U│ < 1.96, then X TN and X DC are not significantly different. The two research results are considered the same. Accept the hypothesis H 0 .

If │U│ > 1.96, then X TN, X DC, are significantly different. The two research results cannot be considered the same. Reject the null hypothesis H 0 . This means that the sample with larger X has better quality. This conclusion has a confidence level of 95%.

APPENDIX 8

RESULTS OF STATISTICAL DATA PROCESSING ON THE SCORES OF THE EXPERIMENTAL AND CONTROL GROUPS BEFORE THE EXPERIMENT IN ROUND 1

Independent Samples Test

APPENDIX 9

RESULTS OF STATISTICAL DATA PROCESSING ON THE SCORES OF THE EXPERIMENTAL AND CONTROL GROUPS AFTER THE EXPERIMENT ROUND 1

Independent Samples Test