Context: I am currently doing my undergraduate research and I am stuck on my analysis part. The study is a quantitative experiment, I had 17 participants performing a maitlands mobilization Grade 3 for 3 times at a time. What I was looking for is if all individuals could exert the same force consistently across the 3 times (i.e. checking for reliability).

Problem: I want to test the Inter-rater reliability and Intra-rater reliability of these participants.

For intra-rater reliability I decided to use ICC in SPSS - One way random and Inter-rater reliability a Two-way random looking at the single measures for both.

However for Intra-rater reliability some of my values came out negative.

Question: Should I be doing a different method? For example, ICC 3,1

How can I interpret the negative values if they are still useful?

Context: I am currently doing my undergraduate research and I am stuck on my analysis part. The study is a quantitative experiment, I had 17 participants performing a maitlands mobilization Grade 3 for 3 times at a time. What I was looking for is if all individuals could exert the same force consistently across the 3 times (i.e. checking for reliability).

Problem: I want to test the Inter-rater reliability and Intra-rater reliability of these participants.

For intra-rater reliability I decided to use ICC in SPSS - One way random and Inter-rater reliability a Two-way random looking at the single measures for both.

However for Intra-rater reliability some of my values came out negative.

Question: Should I be doing a different method? For example, ICC 3,1

How can I interpret the negative values if they are still useful?

I need help! I am currently doing my undergraduate research and I am stuck on my analysis part. The study is a quantitative experiment, I had 17 participants performing a maitlands mobilisation Grade 3 for 3 times at a time. What I was looking for is if all individuals could exert the same force consistently across the 3 times (i.e. checking for reliability). I want to test the Inter-rater reliability and Intra-rater reliability of these participants. For intra-rater reliability I decided to use ICC in SPSS - One way random and Inter-rater reliability a Two-way random looking at the single measures for both. However for Intra-rater reliability some of my values came out negative and I don't know if I should be doing a different method I.e. ICC 3,1 or how to interpret the negative values if they are still useful

Context: I am currently doing my undergraduate research and I am stuck on my analysis part. The study is a quantitative experiment, I had 17 participants performing a maitlands mobilization Grade 3 for 3 times at a time. What I was looking for is if all individuals could exert the same force consistently across the 3 times (i.e. checking for reliability).

Problem: I want to test the Inter-rater reliability and Intra-rater reliability of these participants. 

For intra-rater reliability I decided to use ICC in SPSS - One way random and Inter-rater reliability a Two-way random looking at the single measures for both. 

However for Intra-rater reliability some of my values came out negative.

Question: Should I be doing a different method? For example, ICC 3,1

How can I interpret the negative values if they are still useful?