Anova????

Last night , one of my friend called me to ask about how to test the comparison..... ermmm.. i told him that if there is only two group to be compared.. he can used a T-test if his data is normal.. and if more than 2.. he used apply the anova.... hahahahaa..sound likes the russian.. sharapova... navratilova.. dealova.. and many many lova..hahahhaa until we might be naik loya...

Ok.. since he asked me about anova.. this is an example about how to write the report for anova...

hopefully this will be helpful...

Three or four things to report

You will be reporting three or four things, depending on whether you find a significant result for your 1-Way Betwee Subjects ANOVA

1. Test type and use

You want to tell your reader what type of analysis you conducted. This will help your reader make sense of your results. You also want to tell your reader why this particular analysis was used. What did your analysis test for?

Example

You can report data from your own experiments by using the template below.

“A one-way between subjects ANOVA was conducted to compare the effect of (IV)______________ on (DV)_______________ in _________________,

__________________, and __________________ conditions.”

If we were reporting data for our example, we might write a sentence like this.

“A one-way between subjects ANOVA was conducted to compare the effect of sugar on memory for words in sugar, a little sugar and no sugar conditions.”

2. Significant differences between conditions

You want to tell your reader whether or not there was a significant difference between condition means. You can report data from your own experiments by using the template below.

“There was a significant (not a significant) effect of IV ____________ on DV ______________ at the p<.05 level for the three conditions [F(___, ___) = ___, p = ____].

Just fill in the blanks by using the SPSS output

Let’s fill in the values. You are reporting the degrees of freedom (df), the F value (F) and the Sig. value (often referred to as the p value).

Once the blanks are full…

You have a sentence that looks very scientific but was actually very simple to produce.

“There was a significant effect of amount of sugar on words remembered at the p<.05 level for the three conditions [F(2, 12) = 4.94, p = 0.027].”

3. Only if result of test was significant, report results of post hoc tests

In the previous chapter on interpretation, you learned that the significance value generated in a 1-Way Between Subjects ANOVA doesn’t tell you everything. If you find a significant effect using this type of test, you can conclude that there is a significant difference between some of the conditions in your experiment. However, you will not know where this effect exists. The significant difference could be between any or all of the conditions in your experiment. In the previous chapter, you learned that to determine where significance exists you need to conduct a post hoc test to compare each condition with all other conditions. If you have an IV with 3 levels, like the one in this example, you would need to conduct and report the results of a post hoc test to report which conditions are significantly different from which other conditions.

Example

Because we have found a statistically significant result in this example, we needed to compute a post hoc test. We selected the Tukey post hoc test. This test is designed to compare each of our conditions to every other conditions. This test will compare the Sugar and No Sugar conditions. It will also compare the A little sugar and No Sugar conditions. It will also compare the A Little Sugar and Sugar conditions.  The results of the Tukey post hoc must be reported if you find a significant effect for your overall ANOVA.

You can use the following template to report the results of your Tukey post hoc test. Just fill in the means and standard deviation values for each condition. They are located in your Descriptives box.

If you used this template with our example, you would end up with a sentence that looks something like this.

“Post hoc comparisons using the Tukey HSD test indicated that the mean score for the sugar condition (M = 4.20, SD = 1.30) was significantly different than the no sugar condition (M = 2.20, SD = 0.84). However, the a little sugar condition  (M = 3.60, SD = 0.89) did not significantly differ from the sugar and no sugar conditions.”

4. Report your results in words that people can understand

Since it might be hard for someone to figure out what that sentence means or how it relates to your experiment, you want to briefly recap in words that people can understand. Try to imagine trying to explain your results to someone who is not familiar with science. In one sentence, explain your results in easy to understand language.

Example

You might write something like this for our example.

“Taken together, these results suggest that high levels of sugar really do have an effect on memory for words. Specifically, our results suggest that when humans consume high levels of sugar, they remember more words. However, it should be noted that sugar level must be high in order to see an effect. Medium sugar levels do not appear to significantly increase word memory.”

This sentence is so much easier to understand than the scientific one with all of the numbers in it.

Let’s see how this looks all together

When you put the three main components together, results look something like this.

“A one-way between subjects ANOVA was conducted to compare the effect of sugar on memory for words in sugar, a little sugar and no sugar conditions. There was a significant effect of amount of sugar on words remembered at the p<.05 level for the three conditions [F(2, 12) = 4.94, p = 0.027]. Post hoc comparisons using the Tukey HSD test indicated that the mean score for the sugar condition (M = 4.20, SD = 1.30) was significantly different than the no sugar condition (M = 2.20, SD = 0.84). However, the a little sugar condition  (M = 3.60, SD = 0.89) did not significantly differ from the sugar and no sugar conditions. Taken together, these results suggest that high levels of sugar really do have an effect on memory for words. Specifically, our results suggest that when humans consume high levels of sugar, they remember more words. However, it should be noted that sugar level must be high in order to see an effect. Medium sugar levels do not appear to significantly increase word memory.”

Looks pretty complicated but it is simple when you know how to write each part.