Statistics: Item analysis of spring 2009 midterm
Overall performance on the MS 150 Statistics midterm was strong with a course wide average success rate on the questions of 72%. That is, 57 students correctly answered 72% of the questions posed. The individual item analysis indicated strength in basic statistics, frequency tables, and calculating the slope and intercept for two variable data.
The students had more difficulty when called to make an inference, such as determining whether a z-value was an extraordinary z-value or whether a two-variable relationship was linear or non-linear.
The final question, number 30, asked the students whether linearly projected y-values beyond the domain of the x-values would be valid. Given that the system was non-linear, a linear projection beyond the domain would not yield valid values. All but 11 students missed this inference.
The students excel at making basic single step calculations and do well at well-defined procedures. The students have difficulty when the task requires thinking about the data, analyzing patterns, and making judgment calls based on the data. Finding ways to help the students "step back" from the numbers and make decisions about overall patterns remains a challenge.
The students had more difficulty when called to make an inference, such as determining whether a z-value was an extraordinary z-value or whether a two-variable relationship was linear or non-linear.
qn | Test two spring 2009 | corr | perc |
1 | level of measurement | 43 | 0.75 |
2 | sample size | 56 | 0.98 |
3 | minimum | 57 | 1.00 |
4 | maximum | 57 | 1.00 |
5 | range | 57 | 1.00 |
6 | midrange | 56 | 0.98 |
7 | mode | 56 | 0.98 |
8 | median | 57 | 1.00 |
9 | mean | 48 | 0.84 |
10 | standard deviation | 57 | 1.00 |
11 | coefficient of variation | 48 | 0.84 |
12 | width | 50 | 0.88 |
13 | frequency table | 42 | 0.74 |
14 | frequency histogram | 30 | 0.53 |
15 | shape of histogram | 36 | 0.63 |
16 | probability | 15 | 0.26 |
17 | z-score | 16 | 0.28 |
18 | inference | 16 | 0.28 |
19 | inference | 13 | 0.23 |
20 | slope | 51 | 0.89 |
21 | intercept | 50 | 0.88 |
22 | predict y given x | 38 | 0.67 |
23 | predict x given y | 37 | 0.65 |
24 | nature of relation | 32 | 0.56 |
25 | direction of relation | 47 | 0.82 |
26 | correlation r | 42 | 0.74 |
27 | strength of relation | 43 | 0.75 |
28 | coef determination | 43 | 0.75 |
29 | percent variation acct | 23 | 0.40 |
30 | inference | 11 | 0.19 |
The final question, number 30, asked the students whether linearly projected y-values beyond the domain of the x-values would be valid. Given that the system was non-linear, a linear projection beyond the domain would not yield valid values. All but 11 students missed this inference.
The students excel at making basic single step calculations and do well at well-defined procedures. The students have difficulty when the task requires thinking about the data, analyzing patterns, and making judgment calls based on the data. Finding ways to help the students "step back" from the numbers and make decisions about overall patterns remains a challenge.
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