Findings from item parameters

Estimates of the item parameters are displayed in Table 5-3. The first column contains a description of each item; the second shows the estimated parameter for each item; the following columns are the infit and outfit statistics, which are represented by the forms of both mean square statistics (MnSq) and Z-standardized statistics (Zstd). All the Zstd statistics for these 18 items are in the acceptable range of ± 2, which implies the responses do not significantly deviate from the assumptions of the Rasch model. The items in Table 5-3 have been ordered by their estimated values for comparison purpose.

All the estimates from a Rasch model are relative, thus it is generally suggested to anchor the mean value of all item estimates at zero logit, and then the estimates for each item and person can be calibrated with this reference point. Items with higher estimates on difficulty are those actions or motions which are generally considered to be more difficult to achieve for these elderly passengers; item with lower estimates on difficulty are those actions or motions which are generally considered to be easier to achieve. From Table 5-3, the results show that Item 10 has the highest value among all the item estimates, which indicates that keeping a standing balance when the bus is accelerating or decelerating is the most difficult action for

the elderly bus passengers. Next to that is Item 9, which represents keeping a standing balance on the moving buses. Results from these two item estimates indicate one important cue that standing on a moving bus is the most severe challenge for elderly bus passengers. Combined with the 4^th highest ranking item estimate of keeping balance on the seat of the moving bus (Item 8) and the 6^th highest ranking item estimate of moving to the seat on the bus when it starts to move (Item 7), these results all reflect the elderly passengers’ fear of losing their balance and falling on the moving bus, and they need more protection in order to retain their stability when the bus is in motion.

Table 5-3 Estimates of item measures and fit statistics from Rasch analysis

Infit Outfit

Item b_i

MnSq Zstd MnSq Zstd 10. keeping the standing balance when the bus is accelerating/decelerating 1.69 1.16 0.7 1.17 0.8 9. keeping the standing balance on the running bus 1.12 1.13 0.6 1.11 0.4

2. reading the information at the station 1.08 1.20 0.8 1.24 1.2

8. keeping balance on the seat of the running bus 0.74 1.10 0.5 1.19 0.9

3. discerning the coming bus 0.33 1.27 1.4 1.15 0.7

7. moving to the seat on the bus when it stats to move 0.25 0.98 -0.1 0.96 -0.3 11. realizing the location and direction along the route 0.16 0.94 -0.3 0.91 -0.7

4. beckoning the coming bus -0.14 0.80 -1.5 0.76 -1.9

12. being aware of the coming destination stations -0.19 0.86 -0.9 0.81 -1.4 16. realizing the bus information for the way home -0.25 1.08 0.4 1.06 0.3

5. stepping up the bus -0.26 0.83 -1.1 0.82 -1.1

14. stepping down the bus -0.29 0.86 -0.9 0.84 -1.1

1. walking independently to the station -0.41 0.87 -0.9 0.79 -1.6

17. walking independently to the destination -0.47 0.87 -0.9 0.82 -1.4 18. finding the location of station for returning travel -0.48 0.91 -0.6 0.85 -1.0 15. realizing the walking path to the destination -0.49 0.93 -0.4 0.91 -0.6 13. informing the driver and preparing for getting off the bus -0.84 0.97 -0.2 0.90 -0.7

6. purchasing the ticket on the bus -1.57 0.81 -1.1 0.79 -1.7

Besides the four items related to the elderly passengers’ physical abilities to retain their balance on the moving buses, reading the information posted at the station (Item 2) and

discerning the approaching buses (Item 3) are another two items with relatively high estimates in our findings. These two items are both related to elderly passengers’ visual abilities, which indicate that they need more help or guidance at the station. According to the values of difficulty for these two items, it is noted that elderly passengers might find it more troublesome to read the announced information (static text) than to discern the approaching buses (moving objects), which indicates that the current sizes of words or graphs at the bus station might be too small and unclear for them to read.

Items 11, 12, 15, 16, and 18 are the five items related to elderly bus passengers’ cognitive ability and mental capacity. Except for Item 11 with a smaller positive parameter than the average item measure (zero logit), the other estimates are all negative. It represents that being aware of the location as well as direction on the bus and finding their way home are relatively easy for the elderly passengers. Items 1, 4, 5, 14, and 17 are the five items which were designed to test the elderly passengers’ physical strength and muscle coordination. However, the negative parameters for these item estimates seem to indicate that the elderly bus passengers do not feel very difficult to achieve these requirements such as walking along the streets, waving hands to make a call for the approaching buses, and stepping up or down the bus steps. Stepping up and stepping down the bus are not considered as the difficult tasks by the respondent elderly passengers as expected. We wonder this might be the case that some ground levels and platforms of bus stops have been raised in Taipei City in recent years and further investigation is needed for verification. In all, compared with those items related to balance keeping, it can be seen that the elderly bus passengers generally feel themselves able to act or move well on the stationary buses, but are quite poor on the shaking or moving buses.

The items with the two lowest difficulty estimates are “informing the driver and preparing

to leave the bus (Item 13)” and “purchasing the ticket on the bus (Item 6)”. These results might indicate the current facilities for making a leaving notice to inform the bus driver and for purchasing a ticket are quite suitably designed for elderly passengers in Taipei. The notice bell buttons are commonly installed near passengers’ seats, so that the passengers can push the button and pass the unloading message to the bus driver easily. Purchasing a ticket on the bus is not difficult at all because charge of bus fare in Taipei is commonly made via throwing coins into the fare box or via the contactless electronic payment of EasyCard. Besides, elderly passengers aged over 70 are allowed to travel free in Taipei if they show their senior citizen identification cards. That is why this item was generally regarded as the easiest action by the elderly passengers in Taipei.