Design-based research

How much should educational research techniques mirror natural science research techniques?

What about the research approaches of engineering? Prototyping.

Technology = Application of knowledge

Technology = Creation of knowledge

Technology = Transforming and intervening in the natural world to produce desired results

See handout

Selection skills

Pay close attention to:
1. Data being measured (nominal "categorical", ordinal "ranked", interval "scaled")
2. Number and kind of groups involved
3. Groups are compared or related

SPSS practice

(2) Estimate population mean based on sample mean when sigma is not known (t):

&

(3) Test for statistically significant difference between means (do the intervals overlap?):

SPSS, Analyze, Descriptive Statistics, Explore, Statistics, Confidence Interval
Dependent List = Scaled data variable
Factor List = Grouping variable

Graphing (SPSS, Graphs, Legacy Dialogs, Error Bar) Variable = Scaled data variable, X axis = Grouping variable


Test for statistically significant difference between means (does interval contain zero?) for (4) between groups:

SPSS, Analyze, Compare Means, Independent Samples T-test (Does the interval cross zero? If crosses zero, then no significant difference.)


Test for statistically significant difference between means (does interval contain zero?) for (5) repeated measures:

SPSS, Analyze, Compare Means, Paired Samples T-test (Does the interval cross zero? If crosses zero, then no significant difference.)

Confidence Intervals

The larger the interval range, the more the confidence percentage. People usually set the confidence percentage first and then find the range.

Confidence interval is plus or minus the z score of alpha/2 multiplied by standard error (sigma/square root of n). You can substitute t for z and sigma for s, if you do not know sigma.

"95% confident that the interval includes the parameter." Avoid the "parameter falls between the interval."

Comparing Means With Confidence Intervals

Do the intervals overlap? If yes, no statistical difference. That's it. Replaces Ho testing for between groups and repeated measures.

Confidence Interval for proportions/percentages/pearson r is not tested in this course.

Confidence Interval applications:
1. Estimate population mean based on sample mean when sigma is known (z)
2. Estimate population mean based on sample mean when sigma is not known (t)
3. Test for statistically significant difference between means (do the intervals overlap?)
4. and 5. Test for statistically significant difference between means (does interval contain zero?) for (4) between groups and (5) repeated measures